Fixed #16565 -- Fixed a databrowse error on null foreign key, even though...

Fixed #16565 -- Fixed a databrowse error on null foreign key, even though databrowse is deprecated. Thanks aaugustin for the patch.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@16883 bcc190cf-cafb-0310-a4f2-bffc1f526a37