prezto/git.zsh

# get the name of the branch we are on
function git_prompt_info() {
  ref=$(git symbolic-ref HEAD 2> /dev/null) || return
  branch=${ref#refs/heads/}

  if [[ -d .git ]]; then
    CURRENT_BRANCH="(%{$fg[red]%}${branch}%{$reset_color%})$(parse_git_dirty)"
  else
    CURRENT_BRANCH=''
  fi

  echo $CURRENT_BRANCH
}

parse_git_dirty () {
  [[ $(git status | tail -n1) != "nothing to commit (working directory clean)" ]] && echo " %{$fg[yellow]%}✗%{$reset_color%}"
}