BUG: Series.__getitem__ with MultiIndex and leading integer level
- [x] closes #33355
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

looks good, does your patch also fix these cases by @jorisvandenbossche https://github.com/pandas-dev/pandas/issues/33355#issuecomment-611152308? > does your patch also fix these cases

one of them, am about to push a commit with a test.  the list-like cases no Follow-up coming up that fixes the listlike MultiIndex case as well as a related IntervalIndex bug thanks