Do not process messages with subject AND thread or body as topic changes (#3452)

poezio/core/handlers.py

@@ -1312,6 +1312,8 @@ class HandlerCore:
         """
         Triggered when the topic is changed.
         """
+        if message['body'] or message['thread']:
+            return
         nick_from = message['mucnick']
         room_from = message.get_mucroom()
         tab = self.core.tabs.by_name_and_class(room_from, tabs.MucTab)