Fixed #17937 -- Avoided an error in the timeuntil filter when it receives a...

Fixed #17937 -- Avoided an error in the timeuntil filter when it receives a date object. Thanks Dmitry Guyvoronsky for the report.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@17774 bcc190cf-cafb-0310-a4f2-bffc1f526a37