CLN: test_moments_rolling.py for mean/std/var/count/median/min/max
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
Hello @mroeschke! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:





There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2020-09-27 19:28:46 UTC this is just moving tests around AFAICT right? @jreback exactly. No test addition or subtraction. Just makes it easier to figure out what fails (when I am debugging locally) kk merge on green (i think there is an unrelated fail on 38_numpy_dev but ignore for now)