======================================================================
ERROR: test_foreign_key_to_abstract_model (invalid_models_tests.test_relative_fields.RelativeFieldTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/tim/code/django/tests/invalid_models_tests/test_relative_fields.py", line 272, in test_foreign_key_to_abstract_model
    class AbstractModel(models.Model):
  File "/home/tim/code/django/django/db/models/base.py", line 286, in __new__
    signals.class_prepared.send(sender=new_class)
  File "/home/tim/code/django/django/dispatch/dispatcher.py", line 198, in send
    response = receiver(signal=self, sender=sender, **named)
  File "/home/tim/code/django/django/db/models/fields/related.py", line 92, in do_pending_lookups
    operation(field, sender, cls)
  File "/home/tim/code/django/django/db/models/fields/related.py", line 270, in resolve_related_class
    field.do_related_class(model, cls)
  File "/home/tim/code/django/django/db/models/fields/related.py", line 306, in do_related_class
    self.set_attributes_from_rel()
  File "/home/tim/code/django/django/db/models/fields/related.py", line 303, in set_attributes_from_rel
    self.rel.set_field_name()
  File "/home/tim/code/django/django/db/models/fields/related.py", line 1257, in set_field_name
    self.field_name = self.field_name or self.to._meta.pk.name
AttributeError: 'NoneType' object has no attribute 'name'