Assets.objects behaves strangely

The query set returned from Asset.objects.get_queryset() doesn't seem to behave quite as one would expect.

```python
>>> from assets.models import Asset
>>> Asset.objects.get_base_queryset().count()
1125
>>> Asset.objects.get_queryset().count()
...
TypeError: unhashable type: 'list'
>>> Asset.objects.count()
...
TypeError: unhashable type: 'list'
```