Ambiguity warning printed twice ?

Happy day everyone,

I accidentally noticed a weird behaviour of 'git status'. In a repository I created a branch with the name 'HEAD' by chance. When I run 'git status' in the repository it prints a warning about an ambiguous reference about 'HEAD' which is expected but it prints it twice which seems suspicious.

    $ git branch
      HEAD
      master
    * test

    $ git status
    warning: refname 'HEAD' is ambiguous.
    warning: refname 'HEAD' is ambiguous.
    On branch test
    ....

Any reasons behind this behaviour or is this a bug?