this occurred if a subclass defined __init__ and accessed class
members before calling the superclass __init__
(__getattribute__ had a problem, as "sub_and_superclass_dict" was set in __init__).
=> __init__ + __getattribute__ now handle only the Django inheritance
references that are needed ('modela_ptr', 'modelc' etc.), avoiding
unnecessary conflicts with field names.
by adding related_name to the ContentType ForeignKey. Thanks to Andrew Ingram.
This happened if a polymorphc model used a ContentType ForeignKey.
Plus minor documentation updates.