The valuation comment doesn't show up in the comment show action because
it's not a child of the parent comment. With a regular comment, the test
passes as well.
However, if we make the valuation comment a child of the parent comment,
it shows up both in the index and show actions. That's because the
method `root_descendants` in the `CommentTree` class doesn't filter
valuation comments. I'm not sure whether it's a bug or the intended
behaviour.
49b47dd5f4