problem with position field and south migration

[Martin Schnabel]

when using the south fake orm to migrate a model i get an error.
when changing has_pk in PositionField._set_instance_cache to:

has_pk = hasattr(instance, instance._meta.pk.attname) and bool(getattr(instance, instance._meta.pk.attname))

to check whether the model has an pk field, everything works fine.

[Martin Schnabel]

well and thanks for the effort its a very nice idea

[Joel Watts]

I added code to handle the AttributeError in 1dcacc3. Thanks for letting me know about the problem.