Fixed #7250 -- Don't show internal data of a FileField in the admin when the form does not validate. This also alternatively fixes a recent problem since [8244] when the form is not valid. Thanks Marc Garcia for the initial ticket.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8277 bcc190cf-cafb-0310-a4f2-bffc1f526a37