BUG: Pandas merge DFs on index and column
- [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.

---

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

```python
# Your code here
df = pd.DataFrame([0.5,0.6,6,6,7,12],index=[0,0,1,1,1,2], columns=['distance'])

print(df)

   distance
0       0.5
0       0.6
1       6.0
1       6.0
1       7.0
2      12.0

result = df.merge(df.groupby(df.index)['distance'].min(), left_index=True, right_index=True, on='distance')

print(result)

   distance
0       0.5
0       0.6
1       6.0
1       6.0
1       7.0
2      12.0

```

#### Problem description

Merging two DataFrames using left and right index and a column does not seem to be possible.

I only have two options, reset the index on both DFs and merge on both columns which is slower, or create a multiindex which is unnecessary.

#### Expected Output

```
result = df.reset_index().merge(df.groupby(df.index)['distance'].min().reset_index(), on=['index','distance'])

print(result)

   index  distance
0      0       0.5
1      1       6.0
2      1       6.0
3      2      12.0
```

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

<details>

INSTALLED VERSIONS
------------------
commit           : d9fff2792bf16178d4e450fe7384244e50635733
python           : 3.6.9.final.0
python-bits      : 64
OS               : Linux
OS-release       : 4.19.112+
Version          : #1 SMP Thu Jul 23 08:00:38 PDT 2020
machine          : x86_64
processor        : x86_64
byteorder        : little
LC_ALL           : None
LANG             : en_US.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 1.1.0
numpy            : 1.18.5
pytz             : 2018.9
dateutil         : 2.8.1
pip              : 19.3.1
setuptools       : 49.2.0
Cython           : 0.29.21
pytest           : 3.6.4
hypothesis       : None
sphinx           : 1.8.5
blosc            : None
feather          : 0.4.1
xlsxwriter       : None
lxml.etree       : 4.2.6
html5lib         : 1.0.1
pymysql          : None
psycopg2         : 2.7.6.1 (dt dec pq3 ext lo64)
jinja2           : 2.11.2
IPython          : 5.5.0
pandas_datareader: None
bs4              : 4.6.3
bottleneck       : 1.3.2
fsspec           : 0.8.0
fastparquet      : None
gcsfs            : None
matplotlib       : 3.2.2
numexpr          : 2.7.1
odfpy            : None
openpyxl         : 2.5.9
pandas_gbq       : 0.11.0
pyarrow          : 0.14.1
pytables         : None
pyxlsb           : None
s3fs             : 0.4.2
scipy            : 1.4.1
sqlalchemy       : 1.3.18
tables           : 3.4.4
tabulate         : 0.8.7
xarray           : 0.15.1
xlrd             : 1.1.0
xlwt             : 1.3.0
numba            : 0.48.0

</details>
