'Primary key set correctly with concrete->abstract->concrete inheritance.'

def test_concrete_abstract_concrete_pk(self):

    self.assertEqual(len([field for field in BusStation._meta.local_fields if field.primary_key]), 1)
    self.assertEqual(len([field for field in TrainStation._meta.local_fields if field.primary_key]), 1)
    self.assertIs(BusStation._meta.pk.model, BusStation)
    self.assertIs(TrainStation._meta.pk.model, TrainStation)
