BUG: loc.__getitem__[[na_value]] with CategoricalIndex containing NAs
- [ ] closes #xxxx
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

ok i guess this is worth a whatsnew note, look forward to see how you explain what is changing. Whatsnew added + green