BUG: can't set up dev environment -- Import Error: C extensions: ...
- [x] I have checked that this issue has not already been reported.

- [x] I have confirmed this bug exists on the latest version of pandas.

- [ ] (optional) I have confirmed this bug exists on the master branch of pandas.

---

**Note**: Please read [this guide](https://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports) detailing how to provide the necessary information for us to reproduce your bug.

#### Code Sample, a copy-pastable example

pulled out from #33821 (the main symptom was that `import pandas` failed (see problem description):
> Yea looks like the extensions need to be rebuilt. @charlesdong1991 instructions above should work; maybe not even need the second line if you launch Python from the pandas repo
> […](#)
> On May 19, 2020, at 1:17 PM, Kaiqi Dong ***@***.***> wrote: @charlesdong1991 commented on this pull request. In pandas/tests/plotting/test_frame.py <[#33821 (comment)](https://github.com/pandas-dev/pandas/pull/33821#discussion_r427573721)>: > + def test_color_and_marker(self): + # GH21003 - code sample from 2018-05-10 is equivalent to this test + df = DataFrame(np.random.random((7, 4))) + # combining a color string and a marker letter should be allowed + df.plot(color="green", style="d") # d for diamond + + def test_color_list_and_marker(self): + # GH21003 - code sample from 2020-04-23 is equivalent to this test + df = DataFrame(np.random.random((7, 4))) + color_list = ["yellow", "red", "green", "blue"] + ax = df.plot(color=color_list, style="d") + # Before this patch was introduced, the previous line of code resulted + # in a plot where each individual line was assigned a list of colors: + # ax.lines[i].get_color() == ['yellow', 'red', 'green', 'blue'] + # which resulted in a ValueError when plt.draw() was called. + assert [line.get_color() for line in ax.lines] == color_list emm, have no idea, i really think python setup.py build_ext --inplace -j 4 python -m pip install -e . --no-build-isolation --no-use-pep517 would solve the issue @WillAyd <https://github.com/WillAyd> could you help with the environment issue? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <[#33821 (comment)](https://github.com/pandas-dev/pandas/pull/33821#discussion_r427573721)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAEU4UNW7DTC32C2KAWVF2LRSLSNZANCNFSM4MR622DA>.

I just re-built the pandas-dev environment altogether:

I ran:
```conda env remove --name pandas-dev```

The `pandas-joooeey` folder was still there so I deleted it.

Then I ran in Git Bash:
```
Joey@zenbook MINGW64 ~
$ git clone https://github.com//github.com/joooeey/pandas.git pandas-joooeey
Cloning into 'pandas-joooeey'...
remote: Not Found
fatal: repository 'https://github.com//github.com/joooeey/pandas.git/' not found

Joey@zenbook MINGW64 ~
$ cd pandas-joooeey
bash: cd: pandas-joooeey: No such file or directory

Joey@zenbook MINGW64 ~
$ git clone https://github.com/joooeey/pandas.git pandas-joooeey
Cloning into 'pandas-joooeey'...
remote: Enumerating objects: 226160, done.
remote: Total 226160 (delta 0), reused 0 (delta 0), pack-reused 226160
Receiving objects: 100% (226160/226160), 183.30 MiB | 903.00 KiB/s, done.
Resolving deltas: 100% (188107/188107), done.
Updating files: 100% (1889/1889), done.

Joey@zenbook MINGW64 ~
$ cd pandas-joooeey

Joey@zenbook MINGW64 ~/pandas-joooeey (master)
$ git remote add upstream https://github.com/pandas-dev/pandas.git
```
And then the following commands in Anaconda Prompt (as given by `doskey /history`:
```
(pandas-dev) c:\Users\Joey\pandas-joooeey>doskey /history
cd c:\\users\joey\pandas-joooeey
conda update conda
conda env create -f environment.yml
conda activate pandas-dev
python setup.py build_ext --inplace -j 4
python -m pip install -e . --no-build-isolation --no-use-pep517
python setup.py build_ext --inplace --force
cython --version
doskey /history
```

None of these threw errors. However, I still get an error when I `import pandas` in Spyder (I made sure to open a fresh console in Spyder):
```
import pandas
Traceback (most recent call last):

  File "C:\Users\Joey\pandas-joooeey\pandas\__init__.py", line 32, in <module>
    from pandas._libs import hashtable as _hashtable, lib as _lib, tslib as _tslib

  File "C:\Users\Joey\pandas-joooeey\pandas\_libs\__init__.py", line 13, in <module>
    from pandas._libs.interval import Interval

ModuleNotFoundError: No module named 'pandas._libs.interval'


The above exception was the direct cause of the following exception:

Traceback (most recent call last):

  File "<ipython-input-1-38d4b0363d82>", line 1, in <module>
    import pandas

  File "C:\Users\Joey\pandas-joooeey\pandas\__init__.py", line 40, in <module>
    ) from e

ImportError: C extension: No module named 'pandas._libs.interval' not built. If you want to import pandas from the source directory, you may need to run 'python setup.py build_ext --inplace --force' to build the C extensions first.
```

I also tried re-basing master from upstream in Git Bash:
```
git fetch upstream
git merge upstream/master
git push
```

Console output:

<details>

```
Joey@zenbook MINGW64 ~/pandas-joooeey (master)
$ git fetch upstream
remote: Enumerating objects: 382, done.
remote: Counting objects: 100% (382/382), done.
remote: Compressing objects: 100% (57/57), done.
remote: Total 507 (delta 348), reused 336 (delta 325), pack-reused 125
Receiving objects: 100% (507/507), 239.93 KiB | 813.00 KiB/s, done.
Resolving deltas: 100% (408/408), completed with 168 local objects.
From https://github.com/pandas-dev/pandas
 * [new branch]          0.19.x               -> upstream/0.19.x
 * [new branch]          0.20.x               -> upstream/0.20.x
 * [new branch]          0.21.x               -> upstream/0.21.x
 * [new branch]          0.22.x               -> upstream/0.22.x
 * [new branch]          0.23.x               -> upstream/0.23.x
 * [new branch]          0.24.x               -> upstream/0.24.x
 * [new branch]          0.25.x               -> upstream/0.25.x
 * [new branch]          1.0.x                -> upstream/1.0.x
 * [new branch]          gh-pages             -> upstream/gh-pages
 * [new branch]          master               -> upstream/master
 * [new branch]          revert-25761-patch-1 -> upstream/revert-25761-patch-1
 * [new branch]          revert-29447-orc-reader -> upstream/revert-29447-orc-re
 * [new branch]          v0.25.2.x            -> upstream/v0.25.2.x

Joey@zenbook MINGW64 ~/pandas-joooeey (master)
$ git merge upstream/master
Updating 837daf18d..23c7e85d8
Fast-forward
 .travis.yml                                        |   24 +-
 README.md                                          |    1 +
 asv_bench/benchmarks/algorithms.py                 |   17 +-
 asv_bench/benchmarks/arithmetic.py                 |   63 +-
 asv_bench/benchmarks/groupby.py                    |   58 +
 asv_bench/benchmarks/io/parsers.py                 |    4 +-
 asv_bench/benchmarks/rolling.py                    |   25 +-
 asv_bench/benchmarks/stat_ops.py                   |    4 +-
 azure-pipelines.yml                                |    3 +
 ci/build39.sh                                      |   21 +
 ci/code_checks.sh                                  |    4 +-
 ci/deps/azure-36-minimum_versions.yaml             |    5 +-
 ci/deps/azure-37-numpydev.yaml                     |    5 +-
 ci/deps/azure-macos-36.yaml                        |    2 +-
 ci/deps/travis-37-arm64.yaml                       |   21 +
 ci/run_tests.sh                                    |    2 +-
 ci/setup_env.sh                                    |   19 +-
 conda.recipe/meta.yaml                             |    4 +-
 doc/source/conf.py                                 |    2 +-
 doc/source/development/contributing.rst            |    6 +-
 doc/source/development/extending.rst               |    2 +-
 doc/source/ecosystem.rst                           |   18 +-
 doc/source/getting_started/install.rst             |    2 +-
 .../intro_tutorials/02_read_write.rst              |    6 +-
 .../intro_tutorials/03_subset_data.rst             |    2 +-
 .../intro_tutorials/06_calculate_statistics.rst    |    8 +-
 .../intro_tutorials/07_reshape_table_layout.rst    |   16 +-
 .../intro_tutorials/08_combine_dataframes.rst      |    2 +-
 .../intro_tutorials/09_timeseries.rst              |    6 +-
 .../intro_tutorials/10_text_data.rst               |   20 +-
 doc/source/reference/extensions.rst                |    1 +
 doc/source/reference/general_utility_functions.rst |    4 +
 doc/source/reference/groupby.rst                   |    6 +-
 doc/source/reference/offset_frequency.rst          |   90 +-
 doc/source/user_guide/10min.rst                    |    2 +-
 doc/source/user_guide/basics.rst                   |   75 +-
 doc/source/user_guide/computation.rst              |   38 +-
 doc/source/user_guide/dsintro.rst                  |    6 +-
 doc/source/user_guide/enhancingperf.rst            |   16 +-
 doc/source/user_guide/gotchas.rst                  |    2 +-
 doc/source/user_guide/groupby.rst                  |   94 +
 doc/source/user_guide/indexing.rst                 |    2 +-
 doc/source/user_guide/reshaping.rst                |   14 +-
 doc/source/user_guide/sparse.rst                   |    2 +-
 doc/source/user_guide/timeseries.rst               |   79 +-
 doc/source/whatsnew/v0.18.0.rst                    |   10 +-
 doc/source/whatsnew/v0.18.1.rst                    |   34 +-
 doc/source/whatsnew/v0.19.0.rst                    |   46 +-
 doc/source/whatsnew/v0.19.1.rst                    |    4 +-
 doc/source/whatsnew/v0.19.2.rst                    |    4 +-
 doc/source/whatsnew/v0.20.0.rst                    |   32 +-
 doc/source/whatsnew/v0.20.2.rst                    |   10 +-
 doc/source/whatsnew/v0.20.3.rst                    |    8 +-
 doc/source/whatsnew/v0.21.0.rst                    |   26 +-
 doc/source/whatsnew/v0.21.1.rst                    |   10 +-
 doc/source/whatsnew/v1.1.0.rst                     |  259 ++-
 environment.yml                                    |    4 +-
 pandas/__init__.py                                 |    2 -
 pandas/_libs/groupby.pyx                           |    4 +-
 pandas/_libs/hashtable.pyx                         |    5 +-
 pandas/_libs/hashtable_class_helper.pxi.in         |   44 +-
 pandas/_libs/hashtable_func_helper.pxi.in          |    2 +-
 pandas/_libs/index.pyx                             |   48 +-
 pandas/_libs/internals.pyx                         |    5 +-
 pandas/_libs/interval.pyx                          |   62 +-
 pandas/_libs/lib.pxd                               |    2 +-
 pandas/_libs/lib.pyx                               |   67 +-
 pandas/_libs/missing.pxd                           |    2 +-
 pandas/_libs/missing.pyx                           |   18 +-
 pandas/_libs/parsers.pyx                           |    2 +-
 pandas/_libs/reduction.pyx                         |    4 +-
 pandas/_libs/reshape.pyx                           |    5 +-
 pandas/_libs/src/parser/tokenizer.h                |    4 +-
 pandas/_libs/src/ujson/lib/ultrajson.h             |    2 +-
 pandas/_libs/src/ujson/python/objToJSON.c          |   17 +-
 pandas/_libs/testing.pyx                           |   11 +-
 pandas/_libs/tslib.pyx                             |   32 +-
 pandas/_libs/tslibs/__init__.py                    |   10 +-
 pandas/_libs/tslibs/base.pxd                       |    8 +
 pandas/_libs/tslibs/base.pyx                       |   16 +
 pandas/_libs/tslibs/c_timestamp.pxd                |   17 -
 pandas/_libs/tslibs/c_timestamp.pyx                |  434 ----
 pandas/_libs/tslibs/ccalendar.pxd                  |    4 +
 pandas/_libs/tslibs/ccalendar.pyx                  |    4 +
 pandas/_libs/tslibs/conversion.pyx                 |   77 +-
 pandas/_libs/tslibs/fields.pyx                     |    6 +-
 pandas/_libs/tslibs/frequencies.pxd                |    4 +-
 pandas/_libs/tslibs/frequencies.pyx                |   93 +-
 pandas/_libs/tslibs/nattype.pxd                    |    2 +-
 pandas/_libs/tslibs/nattype.pyx                    |   20 +-
 pandas/_libs/tslibs/np_datetime.pxd                |    2 -
 pandas/_libs/tslibs/np_datetime.pyx                |    9 -
 pandas/_libs/tslibs/offsets.pxd                    |    2 +
 pandas/_libs/tslibs/offsets.pyx                    |  779 ++++++-
 pandas/_libs/tslibs/parsing.pyx                    |   23 +-
 pandas/_libs/tslibs/period.pxd                     |    1 +
 pandas/_libs/tslibs/period.pyx                     |  163 +-
 pandas/_libs/tslibs/resolution.pyx                 |   70 +-
 pandas/_libs/tslibs/strptime.pyx                   |   13 +-
 pandas/_libs/tslibs/timedeltas.pyx                 |  247 +--
 pandas/_libs/tslibs/timestamps.pxd                 |   20 +
 pandas/_libs/tslibs/timestamps.pyx                 |  426 +++-
 pandas/_libs/tslibs/timezones.pxd                  |    9 +-
 pandas/_libs/tslibs/timezones.pyx                  |   21 +-
 pandas/_libs/tslibs/tzconversion.pxd               |    1 -
 pandas/_libs/tslibs/tzconversion.pyx               |   14 +-
 pandas/_libs/tslibs/util.pxd                       |   42 +-
 pandas/_libs/window/aggregations.pyx               |   16 +-
 pandas/_testing.py                                 |   64 +-
 pandas/_typing.py                                  |   16 +
 pandas/compat/__init__.py                          |    1 +
 pandas/compat/_optional.py                         |    2 +-
 pandas/compat/numpy/__init__.py                    |   10 +-
 pandas/compat/numpy/function.py                    |   12 +-
 pandas/compat/pickle_compat.py                     |   38 +
 pandas/conftest.py                                 |   28 +-
 pandas/core/accessor.py                            |    2 +-
 pandas/core/aggregation.py                         |    4 +-
 pandas/core/algorithms.py                          |  100 +-
 pandas/core/array_algos/transforms.py              |    5 +-
 pandas/core/arrays/_mixins.py                      |  122 ++
 pandas/core/arrays/_ranges.py                      |  107 +-
 pandas/core/arrays/base.py                         |   67 +-
 pandas/core/arrays/boolean.py                      |   33 +-
 pandas/core/arrays/categorical.py                  |  166 +-
 pandas/core/arrays/datetimelike.py                 |  537 +++--
 pandas/core/arrays/datetimes.py                    |  138 +-
 pandas/core/arrays/integer.py                      |   38 +-
 pandas/core/arrays/interval.py                     |   26 +-
 pandas/core/arrays/masked.py                       |   35 +-
 pandas/core/arrays/numpy_.py                       |   85 +-
 pandas/core/arrays/period.py                       |   81 +-
 pandas/core/arrays/sparse/array.py                 |   55 +-
 pandas/core/arrays/sparse/dtype.py                 |   26 +-
 pandas/core/arrays/string_.py                      |    9 +
 pandas/core/arrays/timedeltas.py                   |  143 +-
 pandas/core/base.py                                |    7 +-
 pandas/core/common.py                              |   43 +-
 pandas/core/computation/expr.py                    |    2 +-
 pandas/core/computation/expressions.py             |    4 +-
 pandas/core/config_init.py                         |    5 +-
 pandas/core/construction.py                        |   69 +-
 pandas/core/dtypes/base.py                         |   32 +-
 pandas/core/dtypes/cast.py                         |   92 +-
 pandas/core/dtypes/common.py                       |    2 -
 pandas/core/dtypes/concat.py                       |  150 +-
 pandas/core/dtypes/dtypes.py                       |   37 +-
 pandas/core/dtypes/generic.py                      |    2 -
 pandas/core/dtypes/missing.py                      |  123 +-
 pandas/core/frame.py                               |  344 ++-
 pandas/core/generic.py                             |  277 ++-
 pandas/core/groupby/generic.py                     |  178 +-
 pandas/core/groupby/groupby.py                     |  366 +++-
 pandas/core/groupby/grouper.py                     |  156 +-
 pandas/core/groupby/ops.py                         |  129 +-
 pandas/core/indexers.py                            |    2 +-
 pandas/core/indexes/accessors.py                   |    6 +-
 pandas/core/indexes/api.py                         |    3 +-
 pandas/core/indexes/base.py                        |  107 +-
 pandas/core/indexes/category.py                    |   16 +-
 pandas/core/indexes/datetimelike.py                |  279 +--
 pandas/core/indexes/datetimes.py                   |   28 +-
 pandas/core/indexes/extension.py                   |   46 +-
 pandas/core/indexes/interval.py                    |    2 +-
 pandas/core/indexes/multi.py                       |   10 +-
 pandas/core/indexes/numeric.py                     |    4 -
 pandas/core/indexes/period.py                      |   61 +-
 pandas/core/indexes/range.py                       |   14 +-
 pandas/core/indexes/timedeltas.py                  |   35 +-
 pandas/core/indexing.py                            |   45 +-
 pandas/core/internals/__init__.py                  |   10 +-
 pandas/core/internals/blocks.py                    |   40 +-
 pandas/core/internals/concat.py                    |   15 +-
 pandas/core/internals/construction.py              |   69 +-
 pandas/core/internals/managers.py                  |  126 +-
 pandas/core/missing.py                             |  103 +-
 pandas/core/nanops.py                              |  118 +-
 pandas/core/ops/__init__.py                        |   68 +-
 pandas/core/ops/array_ops.py                       |   21 +-
 pandas/core/ops/blockwise.py                       |  102 +
 pandas/core/ops/dispatch.py                        |   14 +-
 pandas/core/ops/docstrings.py                      |    4 +-
 pandas/core/ops/methods.py                         |   10 +-
 pandas/core/resample.py                            |  213 +-
 pandas/core/reshape/concat.py                      |   12 +-
 pandas/core/reshape/melt.py                        |   13 +-
 pandas/core/reshape/merge.py                       |   42 +-
 pandas/core/reshape/pivot.py                       |   40 +-
 pandas/core/reshape/reshape.py                     |    6 +-
 pandas/core/reshape/tile.py                        |   46 +-
 pandas/core/series.py                              |  204 +-
 pandas/core/sorting.py                             |  144 +-
 pandas/core/strings.py                             |   71 +-
 pandas/core/tools/datetimes.py                     |  192 +-
 pandas/core/tools/numeric.py                       |    7 +-
 pandas/core/tools/timedeltas.py                    |    4 +-
 pandas/core/tools/times.py                         |  141 ++
 pandas/core/util/numba_.py                         |   52 +-
 pandas/core/window/common.py                       |   27 +-
 pandas/core/window/ewm.py                          |   10 +-
 pandas/core/window/expanding.py                    |   11 +-
 pandas/core/window/rolling.py                      |  159 +-
 pandas/errors/__init__.py                          |   18 +-
 pandas/io/clipboard/__init__.py                    |    2 +-
 pandas/io/common.py                                |   27 +
 pandas/io/feather_format.py                        |   12 +-
 pandas/io/formats/excel.py                         |   18 +-
 pandas/io/formats/format.py                        |   28 +-
 pandas/io/formats/html.py                          |   10 +-
 pandas/io/formats/info.py                          |   70 +-
 pandas/io/formats/style.py                         |    4 +-
 pandas/io/gcs.py                                   |    6 +-
 pandas/io/json/_json.py                            |    2 +-
 pandas/io/json/_normalize.py                       |    2 +-
 pandas/io/json/_table_schema.py                    |   26 +-
 pandas/io/parquet.py                               |   35 +-
 pandas/io/parsers.py                               |    6 +-
 pandas/io/pickle.py                                |    3 +-
 pandas/io/pytables.py                              |   52 +-
 pandas/io/s3.py                                    |    8 +-
 pandas/io/sas/sas7bdat.py                          |    3 +-
 pandas/io/sas/sas_xport.py                         |    3 +-
 pandas/io/sas/sasreader.py                         |   19 +
 pandas/io/sql.py                                   |    4 +-
 pandas/io/stata.py                                 |  125 +-
 pandas/plotting/_core.py                           |   40 +-
 pandas/plotting/_matplotlib/boxplot.py             |    3 +-
 pandas/plotting/_matplotlib/converter.py           |   59 +-
 pandas/plotting/_matplotlib/core.py                |   10 +-
 pandas/plotting/_matplotlib/hist.py                |    4 +-
 pandas/plotting/_matplotlib/misc.py                |    2 +-
 pandas/plotting/_matplotlib/timeseries.py          |   37 +-
 pandas/plotting/_matplotlib/tools.py               |    2 +-
 pandas/plotting/_misc.py                           |  117 +-
 pandas/tests/api/test_api.py                       |    2 -
 pandas/tests/arithmetic/common.py                  |    9 +-
 pandas/tests/arithmetic/conftest.py                |   28 +-
 pandas/tests/arithmetic/test_datetime64.py         |  147 +-
 pandas/tests/arithmetic/test_interval.py           |   17 +-
 pandas/tests/arithmetic/test_numeric.py            |   10 +-
 pandas/tests/arithmetic/test_period.py             |   74 +-
 pandas/tests/arithmetic/test_timedelta64.py        |  152 +-
 pandas/tests/arrays/boolean/test_logical.py        |    1 +
 pandas/tests/arrays/categorical/test_analytics.py  |   32 +
 .../tests/arrays/categorical/test_constructors.py  |    2 +
 pandas/tests/arrays/categorical/test_missing.py    |   53 +-
 pandas/tests/arrays/integer/test_comparison.py     |   10 +
 pandas/tests/arrays/integer/test_concat.py         |   26 +
 pandas/tests/arrays/integer/test_function.py       |   20 +
 pandas/tests/arrays/sparse/test_array.py           |   19 +
 pandas/tests/arrays/string_/test_string.py         |   55 +
 pandas/tests/arrays/test_datetimelike.py           |  126 +-
 pandas/tests/arrays/test_datetimes.py              |   34 +
 pandas/tests/base/test_conversion.py               |   58 +-
 pandas/tests/base/test_fillna.py                   |    4 +-
 pandas/tests/base/test_misc.py                     |    6 +-
 pandas/tests/base/test_unique.py                   |   10 +-
 pandas/tests/base/test_value_counts.py             |    4 +-
 pandas/tests/dtypes/cast/test_promote.py           |   15 +-
 pandas/tests/dtypes/test_common.py                 |    4 +
 pandas/tests/dtypes/test_dtypes.py                 |    4 +
 pandas/tests/dtypes/test_generic.py                |    6 +-
 pandas/tests/dtypes/test_inference.py              |  117 +-
 pandas/tests/extension/arrow/test_bool.py          |   18 +
 pandas/tests/extension/base/constructors.py        |   33 +
 pandas/tests/extension/base/dtype.py               |    9 +-
 pandas/tests/extension/base/getitem.py             |    3 +-
 pandas/tests/extension/base/methods.py             |   60 +-
 pandas/tests/extension/base/missing.py             |    7 +
 pandas/tests/extension/base/ops.py                 |   18 +-
 pandas/tests/extension/decimal/test_decimal.py     |    4 +
 pandas/tests/extension/json/array.py               |    6 +
 pandas/tests/extension/json/test_json.py           |   35 +-
 pandas/tests/extension/test_boolean.py             |   39 +-
 pandas/tests/extension/test_categorical.py         |   47 +-
 pandas/tests/extension/test_datetime.py            |    9 +
 pandas/tests/extension/test_numpy.py               |   35 +-
 pandas/tests/extension/test_period.py              |   11 +-
 pandas/tests/extension/test_sparse.py              |   12 +
 pandas/tests/extension/test_string.py              |   11 +-
 pandas/tests/frame/indexing/test_indexing.py       |    2 +-
 pandas/tests/frame/methods/test_astype.py          |  559 +++++
 pandas/tests/frame/methods/test_at_time.py         |    4 +
 pandas/tests/frame/methods/test_cov_corr.py        |   27 +
 pandas/tests/frame/methods/test_drop_duplicates.py |    7 +
 pandas/tests/frame/methods/test_interpolate.py     |   12 +
 pandas/tests/frame/methods/test_replace.py         |    8 +
 pandas/tests/frame/methods/test_round.py           |    5 -
 pandas/tests/frame/methods/test_set_index.py       |  532 +++++
 pandas/tests/frame/methods/test_shift.py           |    6 +-
 pandas/tests/frame/methods/test_sort_index.py      |  418 +++-
 pandas/tests/frame/methods/test_sort_values.py     |  162 ++
 pandas/tests/frame/methods/test_truncate.py        |   17 +
 pandas/tests/frame/methods/test_tz_convert.py      |    6 +
 pandas/tests/frame/test_alter_axes.py              |  523 +----
 pandas/tests/frame/test_analytics.py               |   60 +-
 pandas/tests/frame/test_api.py                     |    2 +-
 pandas/tests/frame/test_arithmetic.py              |   19 +-
 pandas/tests/frame/test_axis_select_reindex.py     |    3 +-
 pandas/tests/frame/test_cumulative.py              |   13 +-
 pandas/tests/frame/test_dtypes.py                  |  546 +----
 pandas/tests/frame/test_query_eval.py              |   36 +
 pandas/tests/frame/test_subclass.py                |  133 +-
 pandas/tests/frame/test_to_csv.py                  |    5 +
 pandas/tests/groupby/aggregate/test_aggregate.py   |    8 +
 pandas/tests/groupby/aggregate/test_numba.py       |  115 +
 pandas/tests/groupby/test_apply.py                 |   20 +
 pandas/tests/groupby/test_categorical.py           |   19 +-
 pandas/tests/groupby/test_counting.py              |  135 +-
 pandas/tests/groupby/test_function.py              |  666 +-----
 pandas/tests/groupby/test_groupby_dropna.py        |  244 +++
 pandas/tests/groupby/test_groupby_subclass.py      |   77 +
 pandas/tests/groupby/test_nth.py                   |   12 +
 pandas/tests/groupby/test_nunique.py               |  165 ++
 pandas/tests/groupby/test_pipe.py                  |   78 +
 pandas/tests/groupby/test_quantile.py              |  217 ++
 pandas/tests/groupby/test_size.py                  |   46 +
 pandas/tests/groupby/test_timegrouper.py           |   27 +-
 pandas/tests/groupby/transform/test_numba.py       |    9 +-
 pandas/tests/indexes/categorical/test_astype.py    |   66 +
 pandas/tests/indexes/categorical/test_category.py  |   63 +-
 pandas/tests/indexes/categorical/test_indexing.py  |   37 +
 pandas/tests/indexes/common.py                     |   10 +-
 pandas/tests/indexes/datetimelike.py               |   11 +-
 pandas/tests/indexes/datetimes/test_astype.py      |   47 +-
 .../tests/indexes/datetimes/test_constructors.py   |   15 +-
 pandas/tests/indexes/datetimes/test_date_range.py  |   46 +-
 pandas/tests/indexes/datetimes/test_datetime.py    |   73 +-
 pandas/tests/indexes/datetimes/test_indexing.py    |   42 +-
 pandas/tests/indexes/datetimes/test_insert.py      |   23 +
 pandas/tests/indexes/datetimes/test_map.py         |   41 +
 pandas/tests/indexes/datetimes/test_ops.py         |   42 +-
 .../indexes/datetimes/test_partial_slicing.py      |  104 +-
 pandas/tests/indexes/datetimes/test_pickle.py      |   41 +
 pandas/tests/indexes/datetimes/test_setops.py      |   14 +-
 pandas/tests/indexes/datetimes/test_timezones.py   |   36 +-
 pandas/tests/indexes/interval/test_indexing.py     |    9 +
 pandas/tests/indexes/interval/test_interval.py     |   30 +-
 pandas/tests/indexes/multi/test_analytics.py       |    2 +-
 pandas/tests/indexes/multi/test_indexing.py        |    5 +-
 pandas/tests/indexes/multi/test_join.py            |   12 +-
 .../tests/indexes/multi/test_partial_indexing.py   |   61 +-
 pandas/tests/indexes/multi/test_take.py            |    3 -
 pandas/tests/indexes/numeric/test_astype.py        |   83 +
 pandas/tests/indexes/period/test_astype.py         |   14 +-
 pandas/tests/indexes/period/test_factorize.py      |   37 +
 pandas/tests/indexes/period/test_indexing.py       |   62 +-
 .../tests/indexes/period/test_partial_slicing.py   |  183 +-
 pandas/tests/indexes/period/test_period.py         |   52 -
 pandas/tests/indexes/period/test_period_range.py   |    8 +
 pandas/tests/indexes/period/test_to_timestamp.py   |    3 +-
 pandas/tests/indexes/test_base.py                  |   17 +-
 pandas/tests/indexes/test_common.py                |    4 +-
 pandas/tests/indexes/test_index_new.py             |    5 +-
 pandas/tests/indexes/test_numeric.py               |   76 +-
 pandas/tests/indexes/test_numpy_compat.py          |    4 +-
 .../tests/indexes/timedeltas/test_constructors.py  |   11 +
 pandas/tests/indexes/timedeltas/test_indexing.py   |   14 +-
 pandas/tests/indexes/timedeltas/test_insert.py     |   11 +
 pandas/tests/indexes/timedeltas/test_ops.py        |   25 +-
 .../indexes/timedeltas/test_partial_slicing.py     |   42 +-
 .../tests/indexes/timedeltas/test_searchsorted.py  |   26 +
 pandas/tests/indexes/timedeltas/test_setops.py     |    2 +-
 pandas/tests/indexes/timedeltas/test_timedelta.py  |   32 +-
 .../indexes/timedeltas/test_timedelta_range.py     |   20 +-
 pandas/tests/indexing/multiindex/test_loc.py       |   20 +-
 pandas/tests/indexing/multiindex/test_partial.py   |    3 +-
 pandas/tests/indexing/multiindex/test_slice.py     |   10 +-
 pandas/tests/indexing/multiindex/test_sorted.py    |   30 +-
 pandas/tests/indexing/test_categorical.py          |   22 +-
 pandas/tests/indexing/test_chaining_and_caching.py |    3 -
 pandas/tests/indexing/test_coercion.py             |  150 +-
 pandas/tests/indexing/test_datetime.py             |   13 +-
 pandas/tests/indexing/test_indexing.py             |    3 +-
 pandas/tests/indexing/test_loc.py                  |   13 +
 pandas/tests/indexing/test_partial.py              |  123 +-
 pandas/tests/internals/test_internals.py           |    2 +-
 pandas/tests/io/conftest.py                        |   10 +-
 pandas/tests/io/data/stata/stata-compat-105.dta    |  Bin 0 -> 771 bytes
 pandas/tests/io/data/stata/stata-compat-108.dta    |  Bin 0 -> 1128 bytes
 pandas/tests/io/data/stata/stata-compat-111.dta    |  Bin 0 -> 1514 bytes
 pandas/tests/io/data/stata/stata-compat-113.dta    |  Bin 0 -> 1514 bytes
 pandas/tests/io/data/stata/stata-compat-114.dta    |  Bin 0 -> 1810 bytes
 pandas/tests/io/data/stata/stata-compat-118.dta    |  Bin 0 -> 5798 bytes
 pandas/tests/io/excel/test_openpyxl.py             |    1 -
 pandas/tests/io/excel/test_style.py                |    8 +-
 pandas/tests/io/excel/test_writers.py              |   14 +
 pandas/tests/io/formats/test_css.py                |    2 -
 pandas/tests/io/formats/test_format.py             |   57 +
 pandas/tests/io/json/test_normalize.py             |   20 +
 pandas/tests/io/json/test_pandas.py                |   25 +-
 pandas/tests/io/json/test_ujson.py                 |    3 +-
 pandas/tests/io/parser/test_common.py              |    9 +
 pandas/tests/io/parser/test_dtypes.py              |    3 +-
 pandas/tests/io/parser/test_network.py             |   32 +-
 pandas/tests/io/parser/test_parse_dates.py         |   25 +-
 pandas/tests/io/parser/test_usecols.py             |   10 +-
 pandas/tests/io/pytables/test_store.py             |   64 +-
 pandas/tests/io/pytables/test_timezones.py         |   28 +-
 pandas/tests/io/test_common.py                     |    5 +
 pandas/tests/io/test_feather.py                    |   29 +-
 pandas/tests/io/test_parquet.py                    |   50 +-
 pandas/tests/io/test_sql.py                        |    4 +-
 pandas/tests/io/test_stata.py                      |   74 +-
 pandas/tests/plotting/test_datetimelike.py         |    4 +-
 pandas/tests/plotting/test_hist_method.py          |   24 +
 pandas/tests/reductions/test_reductions.py         |    6 +-
 pandas/tests/resample/test_base.py                 |   36 +-
 pandas/tests/resample/test_datetime_index.py       |  327 ++-
 pandas/tests/resample/test_deprecated.py           |  263 +++
 pandas/tests/resample/test_period_index.py         |   95 +-
 pandas/tests/resample/test_resample_api.py         |    8 +-
 pandas/tests/resample/test_resampler_grouper.py    |   42 +
 pandas/tests/resample/test_time_grouper.py         |   26 +-
 pandas/tests/resample/test_timedelta.py            |   39 +-
 pandas/tests/reshape/merge/test_merge.py           |   32 +-
 pandas/tests/reshape/merge/test_multi.py           |    6 +-
 pandas/tests/reshape/test_concat.py                |   48 +-
 pandas/tests/reshape/test_cut.py                   |   39 +
 pandas/tests/reshape/test_pivot.py                 |   38 +-
 pandas/tests/scalar/interval/test_arithmetic.py    |   47 +
 pandas/tests/scalar/interval/test_interval.py      |    5 +-
 pandas/tests/scalar/period/test_period.py          |   22 +-
 pandas/tests/scalar/test_nat.py                    |    9 +-
 pandas/tests/scalar/timedelta/test_arithmetic.py   |   42 +-
 pandas/tests/scalar/timestamp/test_arithmetic.py   |    2 +-
 pandas/tests/scalar/timestamp/test_comparisons.py  |    4 +-
 pandas/tests/series/indexing/test_alter_index.py   |    2 +
 pandas/tests/series/indexing/test_datetime.py      |    6 +-
 pandas/tests/series/indexing/test_getitem.py       |   13 +
 pandas/tests/series/indexing/test_indexing.py      |   69 +-
 pandas/tests/series/methods/test_asof.py           |    4 +-
 pandas/tests/series/methods/test_astype.py         |   25 +
 pandas/tests/series/methods/test_at_time.py        |    5 +
 pandas/tests/series/methods/test_droplevel.py      |    2 +-
 pandas/tests/series/methods/test_interpolate.py    |   31 +-
 pandas/tests/series/methods/test_rank.py           |    2 +-
 pandas/tests/series/methods/test_shift.py          |    5 +-
 pandas/tests/series/methods/test_sort_index.py     |  154 +-
 pandas/tests/series/methods/test_sort_values.py    |   28 +
 pandas/tests/series/methods/test_to_dict.py        |    8 +-
 pandas/tests/series/methods/test_to_period.py      |   10 +
 pandas/tests/series/methods/test_to_timestamp.py   |   13 +-
 pandas/tests/series/methods/test_truncate.py       |   17 +
 pandas/tests/series/methods/test_tz_localize.py    |    6 +-
 pandas/tests/series/methods/test_update.py         |   54 +-
 pandas/tests/series/test_apply.py                  |   17 +-
 pandas/tests/series/test_arithmetic.py             |   35 +-
 pandas/tests/series/test_constructors.py           |   41 +-
 pandas/tests/series/test_cumulative.py             |   13 +-
 pandas/tests/series/test_datetime_values.py        |    7 +-
 pandas/tests/series/test_dtypes.py                 |    6 +-
 pandas/tests/series/test_io.py                     |    2 +
 pandas/tests/series/test_missing.py                |    9 +-
 pandas/tests/series/test_operators.py              |   54 +-
 pandas/tests/series/test_subclass.py               |   16 +
 pandas/tests/series/test_timeseries.py             |    1 +
 pandas/tests/test_algos.py                         |   72 +
 pandas/tests/test_downstream.py                    |   11 +-
 pandas/tests/test_errors.py                        |    1 +
 pandas/tests/test_expressions.py                   |    2 -
 pandas/tests/test_multilevel.py                    |  328 +--
 pandas/tests/test_strings.py                       |   58 +-
 pandas/tests/test_take.py                          |    2 +-
 pandas/tests/tools/test_to_time.py                 |   15 +-
 pandas/tests/tseries/frequencies/test_freq_code.py |   61 +-
 pandas/tests/tseries/offsets/test_offsets.py       |   51 +-
 .../tseries/offsets/test_offsets_properties.py     |    5 +-
 pandas/tests/tseries/offsets/test_ticks.py         |   27 +-
 pandas/tests/tseries/offsets/test_yqm_offsets.py   |    1 +
 pandas/tests/tslibs/test_api.py                    |    5 +-
 pandas/tests/tslibs/test_conversion.py             |    7 +-
 pandas/tests/tslibs/test_normalize_date.py         |   41 -
 pandas/tests/tslibs/test_period_asfreq.py          |   13 +-
 pandas/tests/util/test_assert_series_equal.py      |   34 +-
 pandas/tests/window/common.py                      |  506 ++---
 pandas/tests/window/conftest.py                    |  215 ++
 pandas/tests/window/moments/conftest.py            |   58 +
 .../window/moments/test_moments_consistency_ewm.py |  279 +++
 .../moments/test_moments_consistency_expanding.py  |  497 +++++
 .../moments/test_moments_consistency_rolling.py    |  695 ++++++
 pandas/tests/window/moments/test_moments_ewm.py    |  661 ++----
 .../tests/window/moments/test_moments_expanding.py |  420 ----
 .../tests/window/moments/test_moments_rolling.py   | 2254 ++++++++------------
 pandas/tests/window/test_api.py                    |  565 ++---
 pandas/tests/window/test_apply.py                  |   30 +-
 pandas/tests/window/test_base_indexer.py           |   76 +-
 pandas/tests/window/test_ewm.py                    |   92 +-
 pandas/tests/window/test_expanding.py              |  264 ++-
 pandas/tests/window/test_rolling.py                |  892 +++++---
 pandas/tests/window/test_window.py                 |  126 +-
 pandas/tseries/frequencies.py                      |   16 +-
 pandas/tseries/offsets.py                          | 1025 ++-------
 pandas/util/_decorators.py                         |   12 +-
 pandas/util/_doctools.py                           |    2 +-
 pandas/util/_validators.py                         |    2 +-
 pyproject.toml                                     |    4 +-
 requirements-dev.txt                               |    4 +-
 scripts/validate_rst_title_capitalization.py       |   17 +
 setup.cfg                                          |    7 +-
 setup.py                                           |    8 +-
 web/pandas/community/blog/extension-arrays.md      |    2 +-
 web/pandas/getting_started.md                      |   16 +-
 web/pandas/static/css/pandas.css                   |    3 +
 504 files changed, 19269 insertions(+), 12424 deletions(-)
 create mode 100755 ci/build39.sh
 create mode 100644 ci/deps/travis-37-arm64.yaml
 create mode 100644 pandas/_libs/tslibs/base.pxd
 create mode 100644 pandas/_libs/tslibs/base.pyx
 delete mode 100644 pandas/_libs/tslibs/c_timestamp.pxd
 delete mode 100644 pandas/_libs/tslibs/c_timestamp.pyx
 create mode 100644 pandas/_libs/tslibs/period.pxd
 create mode 100644 pandas/core/arrays/_mixins.py
 create mode 100644 pandas/core/ops/blockwise.py
 create mode 100644 pandas/core/tools/times.py
 create mode 100644 pandas/tests/arrays/integer/test_concat.py
 create mode 100644 pandas/tests/frame/methods/test_astype.py
 create mode 100644 pandas/tests/frame/methods/test_set_index.py
 create mode 100644 pandas/tests/groupby/aggregate/test_numba.py
 create mode 100644 pandas/tests/groupby/test_groupby_dropna.py
 create mode 100644 pandas/tests/groupby/test_groupby_subclass.py
 create mode 100644 pandas/tests/groupby/test_nunique.py
 create mode 100644 pandas/tests/groupby/test_pipe.py
 create mode 100644 pandas/tests/groupby/test_quantile.py
 create mode 100644 pandas/tests/groupby/test_size.py
 create mode 100644 pandas/tests/indexes/categorical/test_astype.py
 create mode 100644 pandas/tests/indexes/datetimes/test_map.py
 create mode 100644 pandas/tests/indexes/datetimes/test_pickle.py
 create mode 100644 pandas/tests/indexes/numeric/test_astype.py
 create mode 100644 pandas/tests/indexes/period/test_factorize.py
 create mode 100644 pandas/tests/indexes/timedeltas/test_searchsorted.py
 create mode 100644 pandas/tests/io/data/stata/stata-compat-105.dta
 create mode 100644 pandas/tests/io/data/stata/stata-compat-108.dta
 create mode 100644 pandas/tests/io/data/stata/stata-compat-111.dta
 create mode 100644 pandas/tests/io/data/stata/stata-compat-113.dta
 create mode 100644 pandas/tests/io/data/stata/stata-compat-114.dta
 create mode 100644 pandas/tests/io/data/stata/stata-compat-118.dta
 create mode 100644 pandas/tests/resample/test_deprecated.py
 create mode 100644 pandas/tests/scalar/interval/test_arithmetic.py
 create mode 100644 pandas/tests/series/methods/test_astype.py
 delete mode 100644 pandas/tests/tslibs/test_normalize_date.py
 create mode 100644 pandas/tests/window/moments/test_moments_consistency_ewm.py
 create mode 100644 pandas/tests/window/moments/test_moments_consistency_expanding.py
 create mode 100644 pandas/tests/window/moments/test_moments_consistency_rolling.py
 delete mode 100644 pandas/tests/window/moments/test_moments_expanding.py

Joey@zenbook MINGW64 ~/pandas-joooeey (master)
$ git push
Total 0 (delta 0), reused 0 (delta 0), pack-reused 0
To https://github.com/joooeey/pandas.git
   837daf18d..23c7e85d8  master -> master
```

</details>

After that, `import pandas` still results in the same C extension error as given above.

The only thing I left untouched was the Visual Studio Build Tools 2019.

I have the following build tools installed/missing:

Installation details

MSBuild Tools
Provides the tools required to build MSBuild-based applications. 

 
C++ build tools

**Included**

- [x] C++ Build Tools core features
 
- [x] C++ 2019 Redistributable Update

**Optional**

- [x] MSVC v142 - VS 2019 C++ x64/x86 build tools (v14.25)
 
- [x] Windows 10 SDK (10.0.18362.0)
 
- [x] C++ CMake tools for Windows
 
- [x] Testing tools core features - Build Tools
 
- [x] C++ AddressSanitizer (Experimental)
 
- [ ] C++ ATL for latest v142 build tools (x86 & x64)
 
- [ ] C++ MFC for latest v142 build tools (x86 & x64)
 
- [ ] C++/CLI support for v142 build tools (14.25)
 
- [ ] C++ Modules for v142 build tools (x64/x86 – experimental)
 
- [ ] C++ Clang tools for Windows (9.0.0 - x64/x86)
 
- [ ] Windows 10 SDK (10.0.17763.0)
 
- [ ] Windows 10 SDK (10.0.17134.0)
 
- [ ] Windows 10 SDK (10.0.16299.0)
 
- [ ] MSVC v141 - VS 2017 C++ x64/x86 build tools (v14.16)
 
- [ ] MSVC v140 - VS 2015 C++ build tools (v14.00)

#### Problem description

`import pandas` fails on my `master` branch:

```
import pandas
Traceback (most recent call last):

  File "C:\Users\Joey\pandas-joooeey\pandas\__init__.py", line 32, in <module>
    from pandas._libs import hashtable as _hashtable, lib as _lib, tslib as _tslib

  File "C:\Users\Joey\pandas-joooeey\pandas\_libs\__init__.py", line 13, in <module>
    from pandas._libs.interval import Interval

ModuleNotFoundError: No module named 'pandas._libs.interval'


The above exception was the direct cause of the following exception:

Traceback (most recent call last):

  File "<ipython-input-1-38d4b0363d82>", line 1, in <module>
    import pandas

  File "C:\Users\Joey\pandas-joooeey\pandas\__init__.py", line 40, in <module>
    ) from e

ImportError: C extension: No module named 'pandas._libs.interval' not built. If you want to import pandas from the source directory, you may need to run 'python setup.py build_ext --inplace --force' to build the C extensions first.
```

#### Output of ``pd.show_versions()``

N/A -- cannot even import Pandas.

The fork from pandas-dev was made in April 2020.
