[1.2.X] Fixed #10573 -- Corrected autofocus problem in admin when the first...

[1.2.X] Fixed #10573 -- Corrected autofocus problem in admin when the first widget displayed is a multiwidget. Thanks to rduffield for the report, and to Ramiro and Julien Phalip for the patch.

Backport of r15452 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15456 bcc190cf-cafb-0310-a4f2-bffc1f526a37