Refs #17001 -- Added a test for custom prefetch related queryset on generic relations.

            self.assertEqual(sorted([i.tag for i in bookmark.tags.all()]), ["django", "python"])

            self.assertEqual([i.tag for i in bookmark.favorite_tags.all()], ["python"])

    def test_custom_queryset(self):

        bookmark = Bookmark.objects.create(url='http://www.djangoproject.com/')

        django_tag = TaggedItem.objects.create(content_object=bookmark, tag='django')

        TaggedItem.objects.create(content_object=bookmark, tag='python')

        with self.assertNumQueries(2):

            bookmark = Bookmark.objects.prefetch_related(

                Prefetch('tags', TaggedItem.objects.filter(tag='django')),

            ).get()

        with self.assertNumQueries(0):

            self.assertEqual(list(bookmark.tags.all()), [django_tag])

class MultiTableInheritanceTest(TestCase):