Excellent!

I fixed this (if you have ACF) by changing the hook to acf/save_post and I had to change the on_publish_post function to
function on_publish_post($post_id) { $post = get_post($post_id); $new_status = get_post_status($post_id); if($post && $new_status == 'publish') { $id = get_revision_of($post); if ($id) { $original = get_post($id); if ($original) { publish($post, $original); } } } }

@thegaffney Will this change continue to work without ACF? If so, care to create a PR? Thanks for looking into a workable solution!

I'd imagine no, but I think you could just do a simple check like this to see if ACF is installed

if (has_action( 'acf/save_post' ) ) {
     add_action('acf/save_post', __NAMESPACE__.'\\ACF_on_publish_post', 130, 1);
} else {
     add_action('transition_post_status', __NAMESPACE__.'\\on_publish_post', 10, 3);
}

That change still works with ACF, but I won't be able to test it on a site without it, but it seems like it would be the correct way to do it.

Then of course have two on_publish_post functions, one for ACF users

Thanks for the help @thegaffney. I had to modify your changes a bit to make it work with scheduled posts. Will get this up onto WP.org.