$ git clone -n https://src.fedoraproject.org/rpms/rpm.git /var/lib/mock/f41-build-855100-167063/root/chroot_tmpdir/scmroot/rpm
Cloning into '/var/lib/mock/f41-build-855100-167063/root/chroot_tmpdir/scmroot/rpm'...
$ git fetch origin 6da3ebead8555ac2be208d169708ae489d9887f9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rpm
 * [new ref]         6da3ebead8555ac2be208d169708ae489d9887f9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6da3ebe Rebase to 4.20 rc2