Bug 1313137 - "msg is not defined" error in irc.js:changeBuddyNick. r=clokep

--HG--
extra : rebase_source : 5752a69059ecd48b947809ef12de177ccab8528f

chat/protocols/irc/irc.js

@@ -1310,7 +1310,8 @@ ircAccount.prototype = {
       this.conversations.set(aNewNick, conversation);
 
       conversation.updateNick(aNewNick);
-      conversation.writeMessage(aOldNick, msg, {system: true});
+      conversation.writeMessage(aOldNick, _conv("nickSet", aOldNick, aNewNick),
+                                {system: true});
     }
   },