Earlier in the RB7 dev process, I reimplemented the basic functionality

that we needed from django-multiselectfield for a new field in djblets.

This allowed us to resolve runtime issues with multiselectfield and

django 4.0. Unfortunately, there was a problem lurking with

django-evolution signatures, which I didn't notice because I had a

hacked version of multiselectfield installed into my virtualenv.
I've addressed this with a change in django-evolution that adds a

RENAMED_FIELD_TYPES config that can map the module paths from old to

new fields. This allows the django-evolution signature code to import

the field.

Was able to run manage.py evolve --hint and load extensions without

seeing ModuleImportErrors coming from deep inside django-evolution.