$ git clone -n https://src.fedoraproject.org/rpms/obs-service-tar_scm.git /var/lib/mock/f39-build-1704002-41217/root/chroot_tmpdir/scmroot/obs-service-tar_scm
Cloning into '/var/lib/mock/f39-build-1704002-41217/root/chroot_tmpdir/scmroot/obs-service-tar_scm'...
$ git fetch origin dc7abe99c2666ee7a304246437e978b5ddad8512:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/obs-service-tar_scm
 * [new ref]         dc7abe99c2666ee7a304246437e978b5ddad8512 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dc7abe9 New upstream release 0.10.41