Comment 9 for bug 1594239

Yeh I *think* the idea is that you either:
     a) have an instance_id
or
     b) have a unique name
         in which case you're also allowed to have an old compatibility name/instance_id to work with old code that didn't have a unique name (that's in se->compat)

so the assert is:
       assert(!se->compat || se->instance_id == 0);

 The !se->compat corresponds to (a)
     se->instance_id == 0 corresponds to (b)

Having a unique name is a very good idea for hotplug - it lets you unplug the middle one and still receive a migration correctly.

Dave