Use the dateutil library.
I was already using dateutil as an indispensable lib for handling timezones
(See Convert UTC datetime string to local datetime and How do I convert local time to UTC in Python?)
And I’ve just realized it has date parsing support:
import dateutil.parser
yourdate = dateutil.parser.parse(datestring)
(See also How do I translate a ISO 8601 datetime string into a Python datetime object?)