A cached bare clone's HEAD points at refs/heads/<branch>, which is written
once at clone time and never updated again — fetch only touches
refs/remotes/*. Syncs without --ref therefore resolved the frozen
clone-time revision forever: the literal "cached version of the repo"
symptom.
Resolve the default branch via remote.List instead: the advertised HEAD
(plain hash or symref target) is the only source of truth. Verified
against the production Forgejo instance; e2e test fails on the pre-fix
binary and passes now.
