[Glass] Can one get rid of ObsoleteMetaclass instances?

[Pieter Nagel]

I tried to achieve this by forcing the ObsoleteMetaclass instances to be
dirty somehow so that they get written back to the repository in their
"converted to Metaclass3" state.

But this was a no-go, since they are invariant and _beInvariantWhile: is
only defined on Class, not Metaclass3.

Is there any way to force a GemStone object in general to be considered
dirty and written back to disk at commit time?