$ git clone -n https://src.fedoraproject.org/rpms/ocaml-base64.git /var/lib/mock/f38-build-side-42-init-devel-669490-26660/root/chroot_tmpdir/scmroot/ocaml-base64
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-669490-26660/root/chroot_tmpdir/scmroot/ocaml-base64'...
$ git fetch origin cfec2d3979ad427544d13b762f6c82dd7ae50177:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ocaml-base64
 * [new ref]         cfec2d3979ad427544d13b762f6c82dd7ae50177 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cfec2d3 Bump release and rebuild