Fixed #9717 -- Corrected a problem where django-admin.py flush would attempt to flush database tables that had not yet been created. This occurred when an application had been added to INSTALLED_APPS, but had not yet been synchronized. Thanks to Julien Phalip for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9535 bcc190cf-cafb-0310-a4f2-bffc1f526a37