What you want to test instead is the unpickling of queryset pickled in Django < 1.7. You can achieve this by declaring a subclass of `models.QuerySet` that deletes its `django_version` state key:

```python
class MissingDjangoVersionQuerySet(models.QuerySet):
    def __getstate__(self):
        state = super(MissingDjangoVersionQuerySet, self).__getstate__()
        del state['django_version']
        return state

# Add a `missing_django_version_objects = MissingDjangoVersionQuerySet.as_manager()` to `Group`.
```

Then you want to make sure `__setstate__` handles this gracefully, that is raising an `UnpickleException` and not a `KeyError`.