I have a question:

Why does --dirty code path also not call git-update-index and instead does

	setup_work_tree();
	prepare_repo_settings(the_repository);
	the_repository->settings.command_requires_full_index = 0;
	repo_read_index(the_repository);
	refresh_index(...);
	fd = repo_hold_locked_index(...);
	if (0 <= fd)
		repo_update_index_if_able(the_repository, &index_lock);

I assume they are equivalent?
The commit which introduced this --
bb571486ae93d02746c4bcc8032bde306f6d399a (describe: Refresh the index
when run with --dirty) seems to be for the same objective as mu patch.

Is this something you would like to see addressed?

Thanks