Running datetime.strptime against a string containing year, month, day but with a formatter including %H causes a two-digit day to be split across the day and hour fields of the datetime:

datetime.datetime.strptime('20140812', '%Y%m%d%H')
returns: datetime.datetime(2014, 8, 1, 2, 0)
expected: ValueError: time data '20140812' does not match format '%Y%m%d%H'

datetime.datetime.strptime('2014081201', '%Y%m%d%H%M')
returns: datetime.datetime(2014, 8, 12, 0, 1)
expected: ValueError: time data '2014081201' does not match format '%Y%m%d%H%M'

Just noticed the potential for this issue was raised in https://bugs.python.org/msg393688 so it's possible this is not a bug and is the desired behavior, but the documentation doesn't seem to address the issue (unless I'm overlooking it).

I was indeed overlooking the note in the documentation that the leading zero is optional for some formatters when using strptime. Closing.