Debug CI Issue
lint error ```##[error]./pandas/tests/extension/base/dtype.py:1:1:F401:'warnings' imported but unused``` @WillAyd I have  some time over the next couple hours to debug this. I'll plan to push to your branch if that's OK. Ends up being pretty simple. With older numpys

```python
In [24]: pd.DataFrame({"A": pd.array([], dtype="Int64"), "B": pd.array([], dtype="int64")}).dtypes == 'Int64'
Out[24]:
A    True
B    True
dtype: bool

In [25]: np.dtype("int64") == "Int64"
/Users/taugspurger/.virtualenvs/dask-dev/bin/ipython:1: DeprecationWarning: Numeric-style type codes are deprecated and will result in an error in the future.
  #!/Users/taugspurger/Envs/dask-dev/bin/python
Out[25]: True
```

With NumPy master

```python
In [1]: import pandas as pd
i
In [2]: import numpy as np

In [3]: pd.DataFrame({"A": pd.array([], dtype="Int64"), "B": pd.array([], dtype="int64")}).dtypes == 'Int64'
Out[3]:
A     True
B    False
dtype: bool

In [4]: np.dtype("int64") == "Int64"
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-49749ad32aa3> in <module>
----> 1 np.dtype("int64") == "Int64"

TypeError: data type 'Int64' not understood
```

Will push a fix up in a bit. cc @jreback if you have a chance to look. Planning to merge on green to get CI running again though. lgtm merge when ready did we merge something to fix CI? Sorry, thought this was in. Taking another look. Ah, I think this issue is that the numpydev build is NumPy 1.20.dev0.stuff, but it's not new enough to have the changes in the travis-CI job (built from numpy source). Right now https://anaconda.org/scipy-wheels-nightly/numpy/files doesn't have a wheel with the new behavior the travis build (building numpy from source) is seeing.

So it's ugly, but we have to make the check dependent on the behavior of `np.dtype('int64') == "Int64"` until we can get a wheel with the new behavior.  Then we can just check the version number. Maybe just skip the test until the wheel is available?

Sent from my iPhone

> On Jun 12, 2020, at 11:40 AM, Tom Augspurger <notifications@github.com> wrote:
> 
> ﻿
> Right now https://anaconda.org/scipy-wheels-nightly/numpy/files doesn't have a wheel with the new behavior the travis build (building numpy from source) is seeing.
> 
> So it's ugly, but we have to make the check dependent on the behavior of np.dtype('int64') == "Int64" until we can get a wheel with the new behavior. Then we can just check the version number.
> 
> —
> You are receiving this because you were mentioned.
> Reply to this email directly, view it on GitHub, or unsubscribe.
 Slight preference for this, just in case we forget to update or it takes a little while for new wheels to show up.

 No idea why this started failing now

```
        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(
>               scatter_matrix, filterwarnings="always", frame=df, range_padding=0.1
            )

pandas\tests\plotting\test_misc.py:107: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <contextlib._GeneratorContextManager object at 0x000001A3127D1F48>
type = None, value = None, traceback = None

    def __exit__(self, type, value, traceback):
        if type is None:
            try:
>               next(self.gen)
E               AssertionError: Caused unexpected warning(s): [('DeprecationWarning', DeprecationWarning("Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated since Python 3.3,and in 3.9 it will stop working"), 'C:\\Miniconda\\envs\\pandas-dev\\lib\\site-packages\\matplotlib\\cbook\\__init__.py', 2349), ('DeprecationWarning', DeprecationWarning("Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated since Python 3.3,and in 3.9 it will stop working"), 'C:\\Miniconda\\envs\\pandas-dev\\lib\\site-packages\\matplotlib\\cbook\\__init__.py', 2366)]
``` Thanks @TomAugspurger - pretty tricky stuff here @MeeseeksDev backport to 1.0.x Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

```
$ git checkout 1.0.x
$ git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
$ git cherry-pick -m1 e04868400ae3299a69a1901978a18f55650fca9a
```

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

```
$ git commit -am 'Backport PR #34721: Debug CI Issue'
```

4. Push to a named branch :

```
git push YOURFORK 1.0.x:auto-backport-of-pr-34721-on-1.0.x
```

5. Create a PR against branch 1.0.x, I would have named this PR:

> "Backport PR #34721 on branch 1.0.x"

And apply the correct labels and milestones.

Congratulation you did some good work ! Hopefully your backport PR will be tested by the continuous integration and merged soon!

If these instruction are inaccurate, feel free to [suggest an improvement](https://github.com/MeeseeksBox/MeeseeksDev).
                