'Update changes the right number of rows for an empty queryset
when the update affects only a base table'

def test_nonempty_update_with_inheritance(self):

    num_updated = self.a1.d_set.update(y=100)
    self.assertEqual(num_updated, 20)
    cnt = D.objects.filter(y=100).count()
    self.assertEqual(cnt, 20)
