A prompt w/ git status for fish shell

fish_prompt.fish

function fish_prompt --description 'Write out the prompt'
  set -l branch (git branch 2> /dev/null | grep -e '\* ' | sed 's/^..\(.*\)/\1/')
  set -l dirty_count 0

  printf '\n%s' (set_color --bold)(prompt_pwd)(set_color normal)

  if [ $branch ]
    printf ' on %s' (set_color --bold)$branch(set_color normal)
    set -l dirty_count (git status --porcelain | wc -l | sed "s/ //g")

    if test $dirty_count -gt 0
      printf ' %s' (set_color red)●(set_color normal)
    else
      printf ' %s' (set_color blue)●(set_color normal)
    end
  end

  printf "\n> "
end