[ZODB-Dev] 0 is not really equal to my object

[Tim Peters]

[Jim Fulton]
> I'm 99% sure that ZODB 3.3 will read a 3.2 database just fine.

The database format hasn't changed, but some classes no longer appear where
they used to appear, making some older pickles unloadable.  In fact, a
Collector issue was opened about that earlier today:

    http://zope.org/Collectors/Zope/1695

Like `intSet` plain doesn't exist anymore (along with the rest of the old
BTree implementation), and PersistentMapping seems to live under
`persistent.mapping` now.

Don't know what to do about those; don't know why it took so long for anyone
to notice, either.