Fixed #12242 -- Corrected a problem with masking extra selects() in a...

Fixed #12242 -- Corrected a problem with masking extra selects() in a DateQuerySet. Thanks to Alex Gaynor for his help debugging this one.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@11748 bcc190cf-cafb-0310-a4f2-bffc1f526a37