Show the branch name of the vcs

vcs_branch.sh

function vcs_branch {
  local format
  if [[ $# -lt 1 ]]; then
    format="%s"
  else
    format=$1
  fi
  local branch=`_branch`
  if [[ -n $branch ]]; then
    printf $format $branch
  fi
}

function _vcs_branch {
  local dir=`pwd`
  while [[ $dir != `dirname $dir` ]]; do
    for vcs in git hg; do
      if [[ -d "$dir/.$vcs" ]]; then
        case $vcs in
          git) __git_ps1 "git/%s"
            ;;
          hg) echo "hg/`hg branch`"
            ;;
        esac
        return 0
      fi
    done
    dir=`dirname $dir`
  done
}