What do others think?  Is this feasible?

(Rough patch attached; untested.)

I think the patch is wrong (it needs to lookup ids from strings for users, priorities and versions), but otherwise, it is feasible.

I committed the patch with a couple of changes in r87253 using the user ids instead of the names.
I then further improved the patch in r87257 to also check the previous values when they are not changed, so, if the version is already set to e.g. 3.2 and the priority is changed to release blocker (and vice versa -- priority already set to release blocker and 3.2 added), the 3.2 release manager will be added anyway. Finally I fixed a bug in r87259 that gave an error message when the priority was not set.
Attached a diff of all these changes