BUG: pd.cut with bins=1 and input all 0s
The special case of running pd.cut() qith bins=1 an input containing all
0s raises a ValueError

 - [x] closes #15428
closes #15431 
 - [X] tests added / passed
 - [X] passes ``git diff upstream/master | flake8 --diff``
 - [X] whatsnew entry
