python: Prevent extra unexpected reply debug logs.

Since __txn_process_reply always returns None, the existing code
will always hit the final else for replies and log a debug message
about receiving an unexpected reply. In the C version,
ovsdb_idl_txn_process_reply returns true any time the txn is found,
so that behavior is duplicated here.

Signed-off-by: Terry Wilson <twilson@redhat.com>
Signed-off-by: Russell Bryant <russell@ovn.org>

python/ovs/db/idl.py

@@ -649,6 +649,7 @@ class Idl(object):
         txn = self._outstanding_txns.pop(msg.id, None)
         if txn:
             txn._process_reply(msg)
+            return True
 
 
 def _uuid_to_row(atom, base):