flake8 cleanup
Entirely aesthetic.

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hello @jbrockmendel! Thanks for updating the PR.



Cheers ! There are no PEP8 issues in this Pull Request. :beers: 

##### Comment last updated on October 27, 2017 at 21:58 Hours UTC Quick question(s): are we not style-checking this file in the first place?  If not, why haven't we added it to the list of checked files? IIUC its only the diffs that get checked in the CI, so existing flake8 errors pass through. That's not the case, we *should be* linting the entire repository.  However, I think it's because we only lint the `pandas/pandas` directory, and `setup.py` is not in that directory.  Have a look at `lint.sh` and see if you can just add a line for that.

We ask that contributors lint the diff because that's what introduces style-check errors on a PR. # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=h1) Report
> Merging [#17964](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/e1dabf37645f0fcabeed1d845a0ada7b32415606?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/17964/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17964      +/-   ##
==========================================
- Coverage   91.23%   91.22%   -0.02%     
==========================================
  Files         163      163              
  Lines       50113    50113              
==========================================
- Hits        45723    45714       -9     
- Misses       4390     4399       +9
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.03% <ø> (ø)` | :arrow_up: |
| #single | `40.31% <ø> (-0.06%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.75% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17964?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/17964?src=pr&el=footer). Last update [e1dabf3...bf35a27](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=h1) Report
> Merging [#17964](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/dff5109abfd1e29dcd349d04d535a9c8735219b3?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/17964/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17964      +/-   ##
==========================================
- Coverage   91.24%   91.23%   -0.02%     
==========================================
  Files         163      163              
  Lines       50168    50168              
==========================================
- Hits        45778    45769       -9     
- Misses       4390     4399       +9
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.04% <ø> (ø)` | :arrow_up: |
| #single | `40.27% <ø> (-0.06%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.75% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17964?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/17964?src=pr&el=footer). Last update [dff5109...0fadf75](https://codecov.io/gh/pandas-dev/pandas/pull/17964?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @gfyoung is right
this is fine if u also update lint.sh

all flake updates should update the checking code (eg for cython flaking) OK, just added a clause in ci/lint.sh.  I fully expect it to fail for the time being -- is there a mechanism to `xfail`? @jbrockmendel : Not as far as I know.  If you don't mind, why don't you try making a push to patch the remaining issues.  If you have problems, remove the lint command from `lint.sh`, and we can pick it up from where you left off. > OK, just added a clause in ci/lint.sh. I fully expect it to fail for the time being -- is there a mechanism to xfail?

why would you expect a lint on this to fail? isn't that the point here, to make it work? > why would you expect a lint on this to fail? isn't that the point here, to make it work?

The original PR fixed some but not all of the issues.  Following gfyoung's suggestion, I cleaned up the rest of it.  So it should now pass. @jbrockmendel yep looks good now. no merging until after the release (except specifically tagged pr) even though this looks fine, can you rebase (as just added another cython module, indexing.pyx), maybe fine, but just want this to run and go green again. thanks!