CI: cleanup / linting
CI: typo in .travis.yml for print_skipped
CI: linted .travis.yml
CI: removed CLIPBOARD env variables as not used


# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15803?src=pr&el=h1) Report
> Merging [#15803](https://codecov.io/gh/pandas-dev/pandas/pull/15803?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/c577c19d22ac8ec7ea05630576c379e3108248af?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/15803/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/15803?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #15803      +/-   ##
==========================================
- Coverage   91.02%      91%   -0.02%     
==========================================
  Files         143      143              
  Lines       49373    49373              
==========================================
- Hits        44943    44934       -9     
- Misses       4430     4439       +9
```


| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/15803?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/15803?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/15803?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.86% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15803?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15803?src=pr&el=footer). Last update [c577c19...d7a7b35](https://codecov.io/gh/pandas-dev/pandas/pull/15803?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).