Fix bug where a new UUID was occasionaly given to a storage node.

git-svn-id: https://svn.erp5.org/repos/neo/branches/prototype3@463 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/master/app.py

@@ -797,7 +797,8 @@ class Application(object):
 
     def isValidUUID(self, uuid, addr):
         for node in self.nm.getNodeList():
-            if addr != node.getServer() and node.getUUID() == uuid:
+            if node.getUUID() == uuid and node.getServer() is not None \
+                    and addr != node.getServer():
                 return False
         return uuid != self.uuid and uuid != INVALID_UUID