Re: [PATCH 2/4] pack-objects: ensure tree/tag closure with '--stdin-packs=follow'

> Add trees and tags from included and '!' packs (and loose ones with
> '--unpacked') as roots in '--stdin-packs=follow' mode. This rescues
> their descendants even when no input commit reaches them. Walk these
> roots after the existing traversal, preserving the `SEEN` bit to avoid
> redundant traversals. Ensure that the walk takes place *after* the
> existing traversal so that we don't lose the path prefix used for trees
> and blobs wherever possible.

> @@ -3807,6 +3807,7 @@ static int stdin_packs_hints_nr;
>  struct stdin_packs_context {
>  	struct rev_info *revs;
>  	enum stdin_packs_mode mode;
> +	struct oid_array extra_roots;