ImportError:无法导入名称“”prefetch_relations“”

Question

当我尝试运行我的本地django服务器时似乎有一个错误。每当我输入"python manage.py runserver“时，这个错误就会弹出来：

Unhandled exception in thread started by <function check_errors.<locals>.wrapper at 0x042E7C48>
    Traceback (most recent call last):
      File "C:\Python34\lib\site-packages\django\utils\autoreload.py", line 226, in wrapper
        fn(*args, **kwargs)
      File "C:\Python34\lib\site-packages\django\core\management\commands\runserver.py", line 109, in inner_run
        autoreload.raise_last_exception()
      File "C:\Python34\lib\site-packages\django\utils\autoreload.py", line 249, in raise_last_exception
        six.reraise(*_exception)
      File "C:\Python34\lib\site-packages\django\utils\six.py", line 685, in reraise
        raise value.with_traceback(tb)
      File "C:\Python34\lib\site-packages\django\utils\autoreload.py", line 226, in wrapper
        fn(*args, **kwargs)
      File "C:\Python34\lib\site-packages\django\__init__.py", line 18, in setup
        apps.populate(settings.INSTALLED_APPS)
      File "C:\Python34\lib\site-packages\django\apps\registry.py", line 108, in populate
        app_config.import_models(all_models)
      File "C:\Python34\lib\site-packages\django\apps\config.py", line 202, in import_models
        self.models_module = import_module(models_module_name)
      File "C:\Python34\lib\importlib\__init__.py", line 104, in import_module
        return _bootstrap._gcd_import(name[level:], package, level)
      File "<frozen importlib._bootstrap>", line 2231, in _gcd_import
      File "<frozen importlib._bootstrap>", line 2214, in _find_and_load
      File "<frozen importlib._bootstrap>", line 2203, in _find_and_load_unlocked
      File "<frozen importlib._bootstrap>", line 1200, in _load_unlocked
      File "<frozen importlib._bootstrap>", line 1129, in _exec
      File "<frozen importlib._bootstrap>", line 1448, in exec_module
      File "<frozen importlib._bootstrap>", line 321, in _call_with_frames_removed
      File "C:\Python34\lib\site-packages\notify\models.py", line 14, in <module>
        from .utils import prefetch_relations
    ImportError: cannot import name 'prefetch_relations'

有什么办法可以解决这个问题吗？

附注:这个项目一周前还运行得很好