Re: [PATCH] fixup! refs: plumb repo into ref stores

If we are plumbing repo into ref stores, it makes sense to get rid of
the_repository in refs/files-backend.c and use ref_store.repo instead.

Doing that would mean changing some functions (e.g. should_pack_ref())
to take a ref store or repository parameter, and as it is, I'm not sure
if there are still implicit references to the_repository. I think that
all these can be done in a separate patch set.