My custom fish prompt code explained at http://geraldkaszuba.com/tweaking-fish-shell/

fish-git-branch-and-dirty.sh

# Git branch and dirty files
git_branch
if set -q git_branch
    set out $git_branch
    if test $git_dirty_count -gt 0
        set out "$out$c0:$ce$git_dirty_count"
    end
    section git $out
end

How do u axtually use this? Is it just a function? Or do I just include this in my prompt, and the GIT_branch part of your other gist is a function.