Not sure if this works.

git prompt.bash

#!/bin/bash

git_prompt ()
{
    if ! git rev-parse --git-dir > /dev/null 2>&1; then
        return 0
    fi

    git_branch=$(git branch 2>/dev/null| sed -n '/^\*/s/^\* //p')

    if git diff --quiet 2>/dev/null >&2; then
        git_color="${c_git_clean}"
    else
        git_color=${c_git_dirty}
    fi

    echo " [$git_color$git_branch${c_reset}]"
}