BUG: isna_old with td64, dt64tz, period
- [ ] closes #xxxx
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Started as a CLN branch and i left that in for now, can separate if desired.  the bugfix is on L287.
thxs