How to force pandas to display all columns on Travis CI OSX?
#### Code Sample, a copy-pastable example if possible

```python
          >>> import pandas as pd
          >>> from astropy.table import QTable
          >>> import astropy.units as u
          >>> from astropy.time import Time, TimeDelta
          >>> from astropy.coordinates import SkyCoord

          >>> q = [1, 2] * u.m
          >>> tm = Time([1998, 2002], format='jyear')
          >>> sc = SkyCoord([5, 6], [7, 8], unit='deg')
          >>> dt = TimeDelta([3, 200] * u.s)

          >>> t = QTable([q, tm, sc, dt], names=['q', 'tm', 'sc', 'dt'])

          >>> df = t.to_pandas(index='tm')
          >>> with pd.option_context('display.width', 80):
          ...     print(df)
```
#### Problem description

https://travis-ci.org/astropy/astropy/jobs/480019813

Astropy's Travis CI running on OSX somehow is printing
```
        time ...     x
0 1998-01-01 ...   3.0
1 2002-01-01 ...   4.0
```
and not
```
              q  sc.ra  sc.dec       dt
tm
1998-01-01  1.0    5.0     7.0 00:00:03
2002-01-01  2.0    6.0     8.0 00:03:20
```
as expected.

Any advise on how to force `pandas` to expand the `...` on `print()` would be greatly appreciated. We only see this failure on the OSX job, not the other ones running on Linux.

#### Expected Output

```
              q  sc.ra  sc.dec       dt
tm
1998-01-01  1.0    5.0     7.0 00:00:03
2002-01-01  2.0    6.0     8.0 00:03:20
```

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

Version info from pytest header:

```
platform darwin -- Python 3.6.8, pytest-3.10.1, py-1.7.0, pluggy-0.8.0

Running tests with Astropy version 3.2.dev2353.
Running tests in astropy docs.

Date: 2019-01-15T18:25:21

Platform: Darwin-17.4.0-x86_64-i386-64bit

Executable: /Users/travis/miniconda/envs/test/bin/python

Full Python Version: 
3.6.8 |Anaconda, Inc.| (default, Dec 29 2018, 19:04:46) 
[GCC 4.2.1 Compatible Clang 4.0.1 (tags/RELEASE_401/final)]

encodings: sys: utf-8, locale: UTF-8, filesystem: utf-8
byteorder: little
float info: dig: 15, mant_dig: 15

Numpy: 1.15.4
Scipy: 1.1.0
Matplotlib: 3.0.2
h5py: 2.9.0
Pandas: 0.23.4
Asdf: 2.3.1
Cython: 0.29.2
astropy_helpers: 3.1

plugins: remotedata-0.3.1, openfiles-0.3.2, doctestplus-0.2.0, arraydiff-0.3
```

Related issues: astropy/astropy#8331, astropy/astropy#8332, and astropy/astropy#8351