CI / BLD: Various CI Backports
* Pin `blosc` to `1.14.3` (#22429)
* Migrate to CircleCI 2.0 (#21814)
* Pin `openpyxl` to `2.5.5` (#22601)
* Bump `numpy` to `1.9.3` (#22499)
* Fix locale handling (#21739, #22213)
* Upgrade `Cython` to `>=0.28.2` (#21688)
Hello @gfyoung! Thanks for submitting the PR.

 - There are no PEP8 issues in the file [`pandas/tests/indexes/datetimes/test_misc.py`](https://github.com/gfyoung/pandas/blob/8d5793209dd7f30706673505319bd47d64ec2108/pandas/tests/indexes/datetimes/test_misc.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/json/test_compression.py`](https://github.com/gfyoung/pandas/blob/8d5793209dd7f30706673505319bd47d64ec2108/pandas/tests/io/json/test_compression.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/json/test_pandas.py`](https://github.com/gfyoung/pandas/blob/8d5793209dd7f30706673505319bd47d64ec2108/pandas/tests/io/json/test_pandas.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/test_network.py`](https://github.com/gfyoung/pandas/blob/8d5793209dd7f30706673505319bd47d64ec2108/pandas/tests/io/parser/test_network.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/test_excel.py`](https://github.com/gfyoung/pandas/blob/8d5793209dd7f30706673505319bd47d64ec2108/pandas/tests/io/test_excel.py) !

 - There are no PEP8 issues in the file [`pandas/tests/scalar/timestamp/test_timestamp.py`](https://github.com/gfyoung/pandas/blob/8d5793209dd7f30706673505319bd47d64ec2108/pandas/tests/scalar/timestamp/test_timestamp.py) !

 - There are no PEP8 issues in the file [`pandas/tests/series/test_datetime_values.py`](https://github.com/gfyoung/pandas/blob/8d5793209dd7f30706673505319bd47d64ec2108/pandas/tests/series/test_datetime_values.py) !

 @jreback @TomAugspurger : Looks like we need to backport a couple of other things:

* `numpy` version updates (for the `lib.gfortran` errors)

* locale fixes!? (for some reason, `py35_ascii` is picking up way more locales than it does on `master`, causing all of the failures on that build - there are some slight differences in the implementation of `tm.get_locales`, so that might be the cause) # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22637?src=pr&el=h1) Report
> Merging [#22637](https://codecov.io/gh/pandas-dev/pandas/pull/22637?src=pr&el=desc) into [0.23.x](https://codecov.io/gh/pandas-dev/pandas/commit/932de54ac027b9cc8147642ea4448a63fdda33b2?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/22637/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/22637?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           0.23.x   #22637      +/-   ##
==========================================
+ Coverage   91.83%   91.84%   +<.01%     
==========================================
  Files         153      153              
  Lines       49591    49588       -3     
==========================================
- Hits        45544    45543       -1     
+ Misses       4047     4045       -2
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.24% <100%> (ø)` | :arrow_up: |
| #single | `41.79% <100%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/22637?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/22637/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `84.21% <100%> (+0.15%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22637?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/22637?src=pr&el=footer). Last update [932de54...c780f95](https://codecov.io/gh/pandas-dev/pandas/pull/22637?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @jreback @TomAugspurger :

<strike>
* https://travis-ci.org/pandas-dev/pandas/jobs/426221423

Build keeps timing out (seems unrelated with PR though).
</strike>

* https://circleci.com/gh/pandas-dev/pandas/19464
* https://circleci.com/gh/pandas-dev/pandas/19465

Really weird locale failures.

Any thoughts? @jreback @TomAugspurger : Tried doing some more investigation, but still not sure where the locale failures are coming from.  I would like to potentially merge everything up to 2b28893 first, which would address the failures I was seeing in #22634. What's our plan for release? I don't really have a strong desire to do a
0.23.5, especially if it's a pain to backport things.

On Mon, Sep 10, 2018 at 12:39 AM gfyoung <notifications@github.com> wrote:

> @jreback <https://github.com/jreback> @TomAugspurger
> <https://github.com/TomAugspurger> : Tried doing some more investigation,
> but still not sure where the locale failures are coming from. I would like
> to potentially merge everything up to 2b28893
> <https://github.com/pandas-dev/pandas/commit/2b28893e54e073b1c199e759bcb5a164e915cf5b>
> first, which would address the failures I was seeing in #22634
> <https://github.com/pandas-dev/pandas/pull/22634>.
>
> —
> You are receiving this because you were mentioned.
> Reply to this email directly, view it on GitHub
> <https://github.com/pandas-dev/pandas/pull/22637#issuecomment-419792866>,
> or mute the thread
> <https://github.com/notifications/unsubscribe-auth/ABQHIrjGnYfVS3yec0lAGTtOc-rFCyo7ks5uZfsXgaJpZM4Wf8ja>
> .
>
 https://github.com/pandas-dev/pandas/pull/22213 may be the one to fix locales. could pass on 23.5 and just do 24 maybe by end of sept > What's our plan for release? I don't really have a strong desire to do a
0.23.5, especially if it's a pain to backport things.

@TomAugspurger : The "pain" of backporting has been due to CI changes that in hindsight should have been backported earlier than later.  I think we should probably backport changes that:

* Modify existing CI configurations / scripts
* Modify existing tests / testing utilities > #22213 may be the one to fix locales.

@TomAugspurger : Ah, thanks for pointing that out.  Let me see if that solves anything... @jreback @TomAugspurger : Well would you look at that?  That seemed to have done the trick!  All tests are passing now with Circle 2.0.  PTAL. LGTM at a glance, thanks. Feel free to merge when you're ready (probably rebase & merge since it's a backport branch). @TomAugspurger : This is against the `0.23.x` branch, so I think we're good here.