plugin XEP-0280: minor parsing improvement.

libervia/backend/plugins/plugin_xep_0280.py

@@ -118,13 +118,11 @@ class XEP_0280(object):
 
     def message_received_trigger(self, client, message_elt, post_treat):
         """get message and handle it if carbons namespace is present"""
-        carbons_elt = None
         for e in message_elt.elements():
-            if e.uri == NS_CARBONS:
+            if e.uri == NS_CARBONS and e.name in ("received", "sent"):
                 carbons_elt = e
                 break
-
-        if carbons_elt is None:
+        else:
             # this is not a message carbons,
             # we continue normal behaviour
             return True