Fixed #21786: Bad behaviour when mixins + abstract bases for migrations

                    options[name] = model._meta.original_attrs[name]

        # Make our record

        bases = tuple(

            ("%s.%s" % (base._meta.app_label, base._meta.model_name) if hasattr(base, "_meta") else base)

            (

                "%s.%s" % (base._meta.app_label, base._meta.model_name)

                if hasattr(base, "_meta") else

                base

            )

            for base in model.__bases__

            if (not hasattr(base, "_meta") or not base._meta.abstract)

        )

        if not bases:

        # Ensure at least one base inherits from models.Model

        if not any((isinstance(base, six.string_types) or issubclass(base, models.Model)) for base in bases):

            bases = (models.Model, )

        return cls(

            model._meta.app_label,