Updated to use ZODB 3.4a4, featuring savepoints.

doc/CHANGES.txt

@@ -33,6 +33,10 @@ Zope Changes
       - ZCatalog.CatalogBrains: An _unrestrictedGetObject method has
         been added.
 
+      - ZODB transactions now support savepoints. See
+        transaction/savepoint.txt.  These will replace
+        subtransactions.
+
     Bugs fixed
   
       - Collector #1754: Fixed import of 'transaction' in

lib/python/Products/ZODBMountPoint/Mount.py

@@ -201,7 +201,9 @@ class ConnectionPatches:
                         am.closedConnection(conn)
                 conn.cacheGC() # This is a good time to do some GC
                 # XXX maybe we ought to call the close callbacks.
-                conn._storage = conn._tmp = conn.new_oid = conn._opened = None
+                conn._storage = conn._normal_storage = None
+                conn._savepoint_storage = None
+                conn.new_oid = conn._opened = None
                 conn._debug_info = ()
 
                 # collector #1350: ensure that the connection is unregistered