Re: [PATCH v4 6/8] fetch: refactor to make function args narrower

Refactor find_non_local_tags and get_ref_map to only take the
information they need instead of the entire transport struct. Besides
improving code clarity, this also improves their flexibility, allowing
for a different set of refs to be used instead of relying on the ones
stored in the transport struct.

I see that due to the narrowing of get_ref_map() to take the refs (and
the remote) instead of the whole transport, the computation of the refs
(including computation of the ref prefixes) is also moved from
get_ref_map() to its caller, do_fetch(). As in a previous patch,
get_ref_map() is only used once, so this movement is safe.

Reviewed-by: Jonathan Tan <redacted>