$ git clone -n https://src.fedoraproject.org/rpms/calf.git /var/lib/mock/f42-build-side-1-3583191-46888/root/chroot_tmpdir/scmroot/calf
Cloning into '/var/lib/mock/f42-build-side-1-3583191-46888/root/chroot_tmpdir/scmroot/calf'...
$ git fetch origin 8397bc63cd6cb405b647f4291164bc882d1c9060:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/calf
 * [new ref]         8397bc63cd6cb405b647f4291164bc882d1c9060 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8397bc6 0.90.8