[1.1.X] Fixed #12242 -- Corrected a problem with masking extra selects() in a...

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

Backport of r11748 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@11749 bcc190cf-cafb-0310-a4f2-bffc1f526a37