Only update parser state when it is not set.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2003 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/protocol.py

@@ -1622,6 +1622,7 @@ class PacketRegistry(dict):
         data = buf.read(msg_len)
         if data is None:
             # Not enough.
+            if state is None:
                 state_container.set((msg_id, packet_klass, msg_len))
             return None
         if state: