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. Testing Done: Was able to run `manage.py evolve --hint` and load extensions without seeing ModuleImportErrors coming from deep inside django-evolution.