function __git_ps1() {
    GP="";
    until [[ `readlink -f "$GP"` = "/" ]]; do
        if [[ -e "$GP.git/HEAD" ]]; then
            printf "$1" `cat $GP.git/HEAD | sed -re 's/.+\///g'`;
            GP="/";
        else
            GP="$GP../";
        fi
    done
}