Revert "remove notification deleting for disjoining notif chains"

This reverts commit de7a88e90f.

files/routes/comments.py

@@ -364,6 +364,14 @@ def comment(v):
 		post_target.bump_utc = c.created_utc
 		g.db.add(post_target)
 
+	if c.level >= 3 and c.parent_comment.author_id in notify_users:
+		n = g.db.query(Notification).filter_by(
+			comment_id=c.parent_comment.parent_comment_id,
+			user_id=c.parent_comment.author_id,
+			read=True,
+		).one_or_none()
+		if n: g.db.delete(n)
+
 	g.db.flush()
 
 	if c.parent_post: