[BUG?] HEAD detached at HEAD

Hi,

I did a "git checkout --detached", and now I get:

$ git status           
HEAD detached at HEAD
nothing to commit, working directory clean
$ git branch
* (HEAD detached at HEAD)
  master

The "HEAD detached at HEAD" is not very helpful. I thought there was an abbreved sha1 here before, but I'm getting the same with latest Git in master and Git 2.0, so it doesn't seem to be new.

I'm getting it even if there's a tag and/or a branch pointing to the same commit.

Any idea what's going on?