MAINT: test with manylinux numpy/scipy pre-release
Numpy / Scipy switching to daily manylinux wheels of trunk, instead of building
wheels specific to Ubuntu 12.04 for every commit.  Use these new wheels
for numpy and scipy pre-release testing.

See: #15699, #15689 and https://github.com/scipy/scipy/issues/7188.
oh this is nice. thanks @matthew-brett  maybe have the old URL re-direct? My first-pass plan was to find everyone who is using the old URL and update their configs to use the new ones - but it's not a bad idea to redirect.... and that URL is very odd...... @matthew-brett side questions.

- I would not be averse to doing similar wheels for pandas. how are you doing this now? (I assume using travis / circle ci cron?)
- do you know if anyone is building nightly conda packages? (and putting them somewhere)? thanks @matthew-brett  Daily wheels would be excellent!   Yes, it's a travis cron job building on the `daily` branch of `MacPython/numpy-wheels` : 

* https://travis-ci.org/MacPython/numpy-wheels/branches
* https://github.com/MacPython/numpy-wheels/tree/daily # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15702?src=pr&el=h1) Report
> Merging [#15702](https://codecov.io/gh/pandas-dev/pandas/pull/15702?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/fe15466cff9184e38ecee16639c1eefaa45c3c92?src=pr&el=desc) will **decrease** coverage by `0.02%`.
> The diff coverage is `n/a`.


```diff
@@            Coverage Diff             @@
##           master   #15702      +/-   ##
==========================================
- Coverage   91.03%      91%   -0.03%     
==========================================
  Files         143      143              
  Lines       49410    49410              
==========================================
- Hits        44978    44967      -11     
- Misses       4432     4443      +11
```


| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/15702?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/compare/fe15466cff9184e38ecee16639c1eefaa45c3c92...62a9fd18bdd91c6c5e491acb5b6815c56c533ee5?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :x: |
| [pandas/tools/merge.py](https://codecov.io/gh/pandas-dev/pandas/compare/fe15466cff9184e38ecee16639c1eefaa45c3c92...62a9fd18bdd91c6c5e491acb5b6815c56c533ee5?src=pr&el=tree#diff-cGFuZGFzL3Rvb2xzL21lcmdlLnB5) | `93.68% <0%> (-0.34%)` | :x: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/compare/fe15466cff9184e38ecee16639c1eefaa45c3c92...62a9fd18bdd91c6c5e491acb5b6815c56c533ee5?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.87% <0%> (-0.1%)` | :x: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15702?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/15702?src=pr&el=footer). Last update [fe15466...62a9fd1](https://codecov.io/gh/pandas-dev/pandas/compare/fe15466cff9184e38ecee16639c1eefaa45c3c92...62a9fd18bdd91c6c5e491acb5b6815c56c533ee5?el=footer&src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments). so what needs to change here? https://github.com/MacPython/pandas-wheels Have a look at : https://github.com/MacPython/numpy-wheels/blob/master/.travis.yml .   Note `DAILY_COMMIT`.  In the `daily` branch we have `- DAILY_COMMIT=master`.  Then it's just a question of setting up the cron job via the travis-ci interface : https://docs.travis-ci.com/user/cron-jobs/ ok we shall c. in theory it should work. @matthew-brett how does ``DAILY_COMMIT`` get defined? (IOW by the cron on travis?) No, I defined DAILY_COMMIT in the `daily` branch, but another option would be to detect the cron job using something like:

```
if [ "$TRAVIS_EVENT_TYPE" == "cron" ]; then DAILY_COMMIT=master; fi
```

or similar.