Sub-Models of Publishable Models just fail

(Bug, Closed -> Fixed, Priority: Critical, Test Status: No automated tests yet , Reported By Bad Link: Thing 3y284oe not found, )
Publication
Summary: You can create a sub-Model from a Publishable, but attempting to do anything with it crashes.
Unsurprisingly, the issue appears to be that it is getting created in the Publication fork, but Models should always be in the main fork.