NB: I don't have to worry about data invalidation due to aborts and conflicts -
there's only one writer to this database so by design those cannot occur.

So, my question is: if I have a long lasting reference to a PersistentObject
instance, is there a safe way for that object to veto being ghosted by the cache
manager? It looks like reimplementing _p_set_status_ghost as a "pass" might work
but there may be some not so obvious side-effects.

Dave