While creating users, we have several interesting corner cases:
- When creating a new User, we actually rely on the 'unique'
constraint on actor_name. This is important if something calls
'User::createNew' with a name that is already occupied by an
existing anon actor with no user. This is quite a weird corner case,
but there's a test for that. We could probably assimilate this
nicly in actor store by checking whether the user id in the database
for the actor we found is the same as user id in the passed in user identity.
- Even more interesting use-case is 'subsuming' existing actors with
reserved user names. When we call User::newSystemUser, and there is
already an actor with the same reserved name, we 'subsume' that actor
and take over it's actor_id for our new system user. This can now be
done with an upsert. This state of having reserved actor with no user
is not easy to cause, but imports or updating from old MW versions
seem to be able to produce this state. Archeology revealed that
'subsuming' existing actor was added for installer.
Change-Id: I16b2f088217db0283215fc2ef5fb04a3742e1626
021206c232