$ git clone -n https://src.fedoraproject.org/rpms/R-testit.git /var/lib/mock/f45-build-6445-348/root/chroot_tmpdir/scmroot/R-testit
Cloning into '/var/lib/mock/f45-build-6445-348/root/chroot_tmpdir/scmroot/R-testit'...
$ git fetch origin 837a3702b8820cb68deb13e23afbf8e2fa44890c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-testit
 * [new ref]         837a3702b8820cb68deb13e23afbf8e2fa44890c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 837a370 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild