gistfile1.sh

#  *  uncommitted changes
#  ^  stashed changes
#  >  ahead of origin
#  <  behind origin
#  ↕  diverged from origin

function parse_git_dirty() {
  [[ -n $(echo $1 | grep 'nothing to commit (working directory clean)' 2> /dev/null) ]] && echo "*"
}

function parse_git_stash (){
  [[ $(git stash list 2> /dev/null | tail -n1) != "" ]] && echo "^"
}

function parse_git_ahead() {
  [[ -n $(echo $1 | grep 'Your branch is ahead of' 2> /dev/null) ]] && echo ">"
}

function parse_git_behind() {
  [[ -n $(echo $1 | grep 'Your branch is behind' 2> /dev/null) ]] && echo "<"
}

function parse_git_diverge() {
  [[ -n $(echo $1 | grep 'have diverged' 2> /dev/null) ]] && echo "↕"
}

function current_git_branch() {
  git rev-parse --abbrev-ref HEAD 2> /dev/null
}

function current_git_branch_with_markers {
  git_status=`git status 2> /dev/null`
  stash=`parse_git_stash`
  ahead=`parse_git_ahead "$git_status"`
  behind=`parse_git_behind "$git_status"`
  diverge=`parse_git_diverge "$git_status"`
  dirty=`parse_git_dirty "$git_status"`
  echo `current_git_branch` | sed -e "s/\(.*\)/ \[\1$ahead$behind$diverge$dirty$stash\]/"
}

function set_prompt {
  local  GREEN='\[\e[0;32m\]'
  local    RED='\[\e[0;31m\]'
  local NORMAL='\[\e[0m\]'

  PS1="\h:\W \u\[\033[0;32m\]\$(current_git_branch_with_markers) \[\033[0m\]\$ "
}

set_prompt

in function parse_git_dirty(), you need "-z" instead of "-n", I think. As is, the logic seems to be reversed.