$ git clone -n https://src.fedoraproject.org/rpms/buku.git /var/lib/mock/f42-build-3283698-41400/root/chroot_tmpdir/scmroot/buku
Cloning into '/var/lib/mock/f42-build-3283698-41400/root/chroot_tmpdir/scmroot/buku'...
$ git fetch origin 9100c5dc19fd9746ff151df535298c3117a5c13e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/buku
 * [new ref]         9100c5dc19fd9746ff151df535298c3117a5c13e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9100c5d Update to 4.9