For compatibility with Django<=1.10. Replace old
        `_meta.get_concrete_fields_with_model`.
        https://docs.djangoproject.com/en/1.10/ref/models/meta/

def _get_concrete_fields_with_model(self):
        """For compatibility with Django<=1.10. Replace old
        `_meta.get_concrete_fields_with_model`.
        https://docs.djangoproject.com/en/1.10/ref/models/meta/

        """
        return [
            (f, f.model if f.model != self.model else None)
            for f in self.model._meta.get_fields()
            if f.concrete
            and (
                not f.is_relation or f.one_to_one or (f.many_to_one and f.related_model)
            )
        ]