parsedate_tz(): If data is false, return None.  Fixes bug #478115, IndexError when a Date: field exists with an empty value.
parsedate_tz(): If data is false, return None.  Fixes bug #478115,
IndexError when a Date: field exists with an empty value.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator