remove group name from hierarchical tags

tildes/tildes/views/topic.py

@@ -124,6 +124,15 @@ def post_group_topics(
     # remove any tag that's the same as the group's name
     new_topic.tags = [tag for tag in new_topic.tags if tag != str(group.path)]
 
+    # remove the group's name from any hierarchical tag
+    for idx, tag in enumerate(new_topic.tags):
+        split_tag = tag.split(".")
+        if split_tag[0] == str(group.path):
+            tag = ".".join(split_tag[1::])
+            # remove duplicates
+            new_topic.tags[idx] = tag
+    new_topic.tags = list(set(new_topic.tags))
+
     request.apply_rate_limit("topic_post")
 
     request.db_session.add(new_topic)