$ git clone -n https://src.fedoraproject.org/rpms/ocaml-tyxml.git /var/lib/mock/f38-build-side-42-init-devel-600810-26173/root/chroot_tmpdir/scmroot/ocaml-tyxml
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-600810-26173/root/chroot_tmpdir/scmroot/ocaml-tyxml'...
$ git fetch origin b8104705092c46bf6b5902d4e7ece011af616bb1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ocaml-tyxml
 * [new ref]         b8104705092c46bf6b5902d4e7ece011af616bb1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b810470 Rebuild OCaml packages for F38