Ordering of directories in the tree view

I just noticed something surprising in the default (tree) view of a repository: when a repository contains two directories dir and dir-something, the former gets listed after the latter.

Example repo: GitHub - jplatte/testrepo

As you can see, x-1 is listed before x while a-1 is listed after a. This seems like a bug to me and is inconsistent with all local file listing tools I’ve tried.