I mentioned this on the original pull request. This is hard-coded because plana01 is a special machine where our cobbler install lives. It isn't something that should ever change and it seemed bad to just have yet another entry in the teuthology.yaml. I guess I could make it default to that and over-ride it from teuthology.yaml if its really something to be concerned about. This feature will never work for other people as well so it wouldn't be something publicly accessible.