[Zope-Coders] 2.5 -> 2.6 ZClass/Objectmanager breakage

[Anthony Baxter]

ZClasses that are derived from ObjectManager break horribly when
going from Zope2.5 to a newer Zope. The "workaround" involves 
going to the subobject tab, deleting all the metatypes, and
re-creating them on 2.6. This is such a horrid thing to contemplate
(we have a _lot_ of ZClass based products). I'm willing to try
and figure out a fix, would people object to a fix going into the
tree?

(And anyone who answers "don't use ZClasses", yes, thanks, your
input has been noted - it's a bit late now, isn't it...)

Anthony