tor-launcher: please delete the mater branch

I tried to delete an old tor-launcher branch that was created by mistake, but my attempt failed:

 git push origin-rw --delete mater
 remote: + refs/heads/mater tor-launcher brade DENIED by fallthru
 remote: error: hook declined to update refs/heads/mater
 To ssh://git@git-rw.torproject.org/tor-launcher.git
  ! [remote rejected] mater (hook declined)
 error: failed to push some refs to 'ssh://git@git-rw.torproject.org/tor-launcher.git'

My guess is that this is something that a git admin needs to do for us.