Possible kinder GIT-VERSION-GEN?

I have my home directory under git control, and I have a build directory (not tracked by git) under my home directory into which I untar files and then in which I build things, including git.

When doing this, the version reported always contains the '-dirty' suffix, which I find annoying (and potentially misleading). I traced this to the GIT-VERSION-GEN script, and I "fixed" it by checking if there is a '.git' directory present before invoking git diff-index, something like this:

dirty=$(sh -c 'test -f .git && git diff-index --name-only HEAD' 2>/dev/null) || dirty=
case "$dirty" in
'')
        ;;
*)
        VN="$VN dirty" ;;
esac

If someone of authority here thinks this seems reasonable (or has a better way), I will test this (along with any suggested improvements) with the git repo itself (to ensure it puts '-dirty' when it really should), and submit a patch.

Bill