Merge branch 'jk/fetch-ref-prefix-cleanup'

In protocol v2 where the refs advertisement is constrained, we try to tell the server side not to limit the advertisement when there is no specific need to, which has been the source of confusion and recent bugs. Revamp the logic to simplify. * jk/fetch-ref-prefix-cleanup: fetch: use ref prefix list to skip ls-refs fetch: avoid ls-refs only to ask for HEAD symref update fetch: stop protecting additions to ref-prefix list fetch: ask server to advertise HEAD for config-less fetch refspec_ref_prefixes(): clean up refspec_item logic t5516: beef up exact-oid ref prefixes test t5516: drop NEEDSWORK about v2 reachability behavior t5516: prefer "oid" to "sha1" in some test titles t5702: fix typo in test name