Compatibility fix for ZODB 3.4

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2818 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/client/__init__.py

@@ -94,7 +94,10 @@ if needs_patch:
         # I don't know any legitimate use of DB access outside a transaction.
 
         def afterCompletion(self, *ignored):
+            try:
                 self._readCurrent.clear()
+            except AttributeError: # old ZODB (e.g. ZODB 3.4)
+                pass
             self._flush_invalidations()
         Connection.afterCompletion = afterCompletion