Show git branch and dirty state on prompt

gistfile1.sh

#   Display the current git branch and wether its dirty
#   https://gist.github.com/964107/
#   username@Machine ~/dev/dir[master]$   # clean working directory
#   username@Machine ~/dev/dir[master*]$  # dirty working directory
#   username@Machine ~/dev/dir[master](1↑2↓)$   # clean working directory, but changes incoming and outgoing

function parse_git_dirty {
  [[ $(git status 2> /dev/null | tail -n1) != "nothing to commit, working directory clean" ]] && echo "*"
}
function git_ahead_behind {
  ~/.git_ahead_behind.rb
}
function parse_git_branch {
  git branch --no-color 2> /dev/null | sed -e '/^[^*]/d' -e "s/* \(.*\)/[\1$(parse_git_dirty)]/"
}
export PS1='\u@\h \[\033[1;33m\]\w\[\033[0m\]$(parse_git_branch)$(git_ahead_behind)$ '