git-archive and submodules

(Please note that I am not subscribed to the mailing list, so if you
want me to read your reply, it must be sent to
woody.gilk@kohanaphp.com)

I would find it hugely valuable if git-archive would support
submodules, rather than leaving empty files in the place of
submodules. Supporting submodules is critical to packaging releases
(combined with signed tags). With git-archive not support submodules,
it means that I have to manually package and sign each release, rather
than using git-tag.

This seems like it should be a fairly trivial thing to support,
possibly with the addition of a --with-submodules parameter for
git-archive to avoid backwards compatibility issues.

Thank you,
-Woody Gilk
Lead Developer of Kohana PHP Framework