/todo doesn't work when closing an existing todo

Here's what I do:

1. I have a todo on an issue.

2. I want to add a comment, and create a new todo.

3. I comment with:

   Looks good to me!
   /todo

What I expect to happen: the comment is added and I get a todo for the issue.

What actually happens: the comment is added and I don't get a new todo.

@rymai is what I'm expecting reasonable?