Use conversation.get_nick() instead of conversation.nick when adding a

message to a conversation tab.

When you rename one of your contact and have a conversation opened, the
nickname wasn't updated when you received new messages.

poezio/core/handlers.py

@@ -270,8 +270,8 @@ class HandlerCore:
 
         if not own and not conversation.nick:
             conversation.nick = remote_nick
-        elif not own: # keep a fixed nick during the whole conversation
-            remote_nick = conversation.nick
+        elif not own:
+            remote_nick = conversation.get_nick()
 
         self.core.events.trigger('conversation_msg', message, conversation)
         if not message['body']: