as seen in yannk++, but remove debian-specific stuff

git-prompt-dirty.sh

# add in your .bashrc
# http://henrik.nyh.se/2008/12/git-dirty-prompt
# http://www.simplisticcomplexity.com/2008/03/13/show-your-git-branch-name-in-your-prompt/
# http://blog.cyberion.net/2009/01/improved-bash-prompt-for-git-usage.html
#   username@Machine ~/dev/dir[master]$   # clean working directory
#   username@Machine ~/dev/dir[master⚡]$  # dirty working directory
#
# I've made the following ajustements:
#   - Use of plumbing, that should be faster than git status porcelain.
#   - Don't show my repo as dirty if it has files unknown from the index (I always have).
#   - Integrated to debian's PS1 (trivial to adapt) and uses standard __git_ps1 from bash_completion

# NOTE: if you notice bash weirdness, disable colors
function __git_dirty {
    local dirty RED NO_COLOR
    RED="\033[0;31m"
    NO_COLOR="\e[0m"
    dirty=$(git diff-index --cached --quiet HEAD 2>/dev/null || echo "⚡")
    if [ ! -z "$dirty" ]; then
        echo "${RED}${dirty}${NO_COLOR}";
        return;
    fi
    dirty=$(git diff-index --quiet HEAD 2>/dev/null || echo "⚡")
    [ -z "$dirty" ] && return
    echo "${RED}${dirty}${NO_COLOR}";
}

PS1='\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;36m\]\W\[\033[00m\]$(__git_ps1 " [%s$(__git_dirty)]")\$ '