plugin XEP-0045: fixed issue with deepcopy by using new xml_tools.elementCopy method

sat/plugins/plugin_xep_0045.py

@@ -30,7 +30,6 @@ from sat.memory import memory
 
 import time
 import uuid
-import copy
 
 from wokkel import muc, disco, iwokkel
 from sat.tools import xml_tools
@@ -761,7 +760,7 @@ class XEP_0045(object):
         # XXX: shouldn't it be done by the server ?!!
         muc_client = client._muc_client
         for room_jid, room in muc_client.joined_rooms.iteritems():
-            elt = copy.deepcopy(presence_elt)
+            elt = xml_tools.elementCopy(presence_elt)
             elt['to'] = room_jid.userhost() + '/' + room.nick
             client.presence.send(elt)
         return True