Previous code triggered a conversion from unicode to ascii inside the
django framework, which would throw an exception when the object itself
returned unicode in the name.
The new version will work around that by actually checking the primary
key first.
This still doesn't work insofar that any changes to a many2many fields
are now lost. This did not work properly before either, but this
probably made it a bit work. We definitely need to fix this properly at
some point, probably by using the m2m_changed signal handler (but it's
not straight forward as this is now a separate signal and we'll somehow
want to track this indepdendently)
We were already using signals for everything except delete, and even
in our old version of django the delete signal exists (it didn't exist
when this code was first written).
Django doesn't really like models to be OOP like this, so keeping PgModel
would cause issues with upcoming changes in django 1.8. Using simple functions
is easier, and the actual functionality is replicated straight off.
