Backport PR #38099: BUG: fix wrong error message in deprecated 2D indexing of Series with datetime values
Backport PR #38099 on branch 1.1.x
@jorisvandenbossche the test failures are the same as master. was the change in https://github.com/pandas-dev/pandas/pull/38210/commits/e350b8215e2ec4a49c7ee2fb991ec898ee44e486 needed?

merge when ready. >  was the change in e350b82 needed?

Yeah, the ``__getitem__`` behaviour of DatetimeArray has apparently quite changed on master, so it didn't work directly on 1.1.x. This does the conversion to a numpy array first, on the 1D EA, and only then does the 2D indexing operation. This seemed relatively safe to do Thanks @jorisvandenbossche 