Inconsistency in strftime between python 3.6 and 3.7 when parsing first-century dates.

Python 3.6
>>> datetime.datetime.strptime(d, "%Y-%m-%d").strftime("%Y-%m-%d")
'0020-10-05'

Python 3.7
>>> datetime.datetime.strptime("0020-10-05", "%Y-%m-%d").strftime("%Y-%m-%d")
'20-10-05'

This means that the following would work for 3.6 but raise a ValueError for 3.7:

>>> d = "0020-10-05"
>>> d = datetime.datetime.strptime(d, "%Y-%m-%d").strftime("%Y-%m-%d")
>>> d = datetime.datetime.strptime(d, "%Y-%m-%d").strftime("%Y-%m-%d")