Re: [RFC PATCH 1/2] refs: make _advance() check struct repo, not flag

quoted

Yes, the packed backend doesn't need to be a ref backend.

Sorry, I do not follow.  Do you mean we cannot have a version of Git
that offers say a read-only access to the repository without any
loose refs, with the default ref backend being the packed one?

Or do you mean that we can ignore such a hypothetical use case and
could reimplement the files backend that can also understand the
$GIT_DIR/packed-refs file directly without "deferring to another ref
backend which is 'packed'"?

I meant the latter - more specifically, the files backend could defer to
functions that are not necessarily inside a struct ref_storage_be.