Heads up! If you have a Zope trunk checkout, you'll need to recursively delete directory lib/python/Persistence before an update will succeed. If you try to update before deleting that directory, you'll see something like: Failed to add directory 'lib/python/Persistence': object of the same name already exists. You may also need to do "svn cleanup" and try again, if you don't delete the directory before trying to update. [Tim Peters]
If there are no sane <wink> objections, I'd like to move Zope trunk to using ZODB 3.5 tomorrow (Friday). ...
This didn't happen. There's a chicken-and-egg problem with incorporating zpkg changes too, and that's probably going to wait for a newer release of Five.
A related changed would happen soon after (probably also on Friday): the ExtensionClass-based Persistence package still lives in the ZODB part of the repository, despite that it can't even be compiled from a ZODB checkout (the prerequisite ExtensionClass implementation lives in the Zope part of the repository). So the plan there is to remove the svn:externals stitching Persistence into Zope from ZODB, and move the Persistence package from ZODB trunk to Zope trunk.
That part did happen. Removing the svn:externals line for Persistence from Zope trunk's lib/python, followed by an ``svn move`` of the Persistence package (from ZODB trunk to Zope trunk), caused the headaches at the top of this message. I'm afraid current SVN gets a bit lost when switching from copies to externals, or vice versa.