Fixed #13177 -- Corrected usage of firstof in admin templates. Thanks to...

Fixed #13177 -- Corrected usage of firstof in admin templates. Thanks to nomulous for the report and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12840 bcc190cf-cafb-0310-a4f2-bffc1f526a37