Django 多态模型在 1.7 上进行迁移时出现问题

我在我的模型中使用 Django 1.7 和 django-polymorphic

class ReferenceItem(PolymorphicModel):
    created_at = models.DateTimeField(_('date created'), auto_now_add=True, db_index=True)
    updated_at = models.DateTimeField(_('date modified'), auto_now=True, db_index=True)
    uuid = UUIDField(auto=True, unique=True)
    description = models.CharField(max_length=255)

class OrderItem(ReferenceItem):
    order = models.ForeignKey('Order', related_name='items')
    sku = models.CharField(max_length=255)
    quantity = models.IntegerField()
    unit_price = models.DecimalField(max_digits=10, decimal_places=2)
    amount = models.DecimalField(max_digits=10, decimal_places=2)
    tax_rate = models.DecimalField(max_digits=3, decimal_places=2)
    commission_rate = models.DecimalField(max_digits=3, decimal_places=2)

当我跑的时候makemigrations我收到这个错误：

raise InvalidBasesError("Cannot resolve bases for %r\nThis can happen if you are inheriting models from an app with migrations (e.g. contrib.auth)\n in an app with no migrations; see https://docs.djangoproject.com/en/1.7/topics/migrations/#dependencies for more" % new_unrendered_models)
django.db.migrations.state.InvalidBasesError: Cannot resolve bases for [<ModelState: 'orders.OrderItem'>]
This can happen if you are inheriting models from an app with migrations (e.g. contrib.auth)

我已经通过djangoticket https://code.djangoproject.com/ticket/22708但仍然不知道问题是什么。

我猜这与多态包无关。

我所做的修复方法是注释掉我的应用程序，保留内置的 django 应用程序，运行./manage.py migrate迁移系统应用程序，然后取消注释我的应用程序，然后运行./manage.py makemigrations