Remove unused cimports, fix #22067
Fixes #22067, but no clear way to test it.

- [x] closes #22067

minor comments and pls rebase Hello @jbrockmendel! Thanks for updating the PR.



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

##### Comment last updated on July 29, 2018 at 20:57 Hours UTC # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22087?src=pr&el=h1) Report
> Merging [#22087](https://codecov.io/gh/pandas-dev/pandas/pull/22087?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/d30c4a0696d5fbdc3c7ce36a9b9b19224a557e09?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/22087/graphs/tree.svg?height=150&width=650&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/22087?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #22087   +/-   ##
=======================================
  Coverage   92.07%   92.07%           
=======================================
  Files         170      170           
  Lines       50690    50690           
=======================================
  Hits        46672    46672           
  Misses       4018     4018
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.48% <ø> (ø)` | :arrow_up: |
| #single | `42.31% <ø> (ø)` | :arrow_up: |


------

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> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22087?src=pr&el=footer). Last update [d30c4a0...a1bff36](https://codecov.io/gh/pandas-dev/pandas/pull/22087?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Ping thanks!