BUG: DTA/TDA incorrectly accepting iNaT for setitem
- [ ] closes #xxxx
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

First of several related PRs.
@TomAugspurger the Travis failure here seems to be affecting everything.  The traceback looks like its somewhere in xdist or pytest.  Didn't we recently deal with something really similar? Yeah, I think pytest 5.x is incompatible with pytest-xdist<=1.28

pytest                    5.0.1                    py36_0
pytest-forked             1.0.2                    py36_0
pytest-mock               1.10.4                   py36_0
pytest-xdist              1.28.0                     py_0


So probably bump pytest-xdist>=1.29 in this env if possible.

On Thu, Aug 1, 2019 at 2:08 PM jbrockmendel <notifications@github.com>
wrote:

> @TomAugspurger <https://github.com/TomAugspurger> the Travis failure here
> seems to be affecting everything. The traceback looks like its somewhere in
> xdist or pytest. Didn't we recently deal with something really similar?
>
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 green thanks