separate out M2Ms at the point of type conversion rather than assignment -- it's simpler this way
separate out M2Ms at the point of type conversion rather than assignment -- it's simpler this way

Test Plan: .

Reviewers: noemi

Subscribers: noemi, bkanber

Maniphest Tasks: T3061

Differential Revision: http://ph.dev.tid.al/D1483

TidalLabs/django-phabricator,TidalLabs/django-phabricator