Fixed #7097 -- dates() queries now work as expected with select_related() --...

Fixed #7097 -- dates() queries now work as expected with select_related() -- that is, select_related() has no effect on the query. Thanks for reporting, Marco

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7486 bcc190cf-cafb-0310-a4f2-bffc1f526a37