[1.2.X] Fixed #14012 -- Corrected the handling of the create user popup dialog...

[1.2.X] Fixed #14012 -- Corrected the handling of the create user popup dialog in the admin. Thanks to gk@lka.hu for the report, and Ramiro Morales for the patch.

Backport of r13051 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@13502 bcc190cf-cafb-0310-a4f2-bffc1f526a37