This commit fixes two different issues:
* In some cases, when an object was added to a sub-collection and used
into a different subcollection, and the root common collection would
not need to be resynced, it would end up creating multiple overrides
of the new object. This was affecting both normal and recursive
resync.
* In recurisve resync case, the barrier code to define what is part or
not of a override group/hierarchy was wrong.
Note that the current solution for the first issue is sub-optimal (it
goes back to the root of the override hierarchy and resync the whole
thing), a better solution is TODO for now.
bf8659930f