We had a regression in repository saving where the user and group access

lists weren't being saved. While users would be validated against the

user list, any changes made would be thrown out. The solution was to add

a save_m2m() call (which is needed when choosing not to immediately

save the model to the database through commit=False). Unit tests were

added to catch regressions here in the future.

Unit tests pass.
Verified manually that I could alter the users and groups lists without

any problems.