$ git clone -n https://src.fedoraproject.org/rpms/R-lokern.git /var/lib/mock/f45-build-6224-347/root/chroot_tmpdir/scmroot/R-lokern
Cloning into '/var/lib/mock/f45-build-6224-347/root/chroot_tmpdir/scmroot/R-lokern'...
$ git fetch origin 20e0f8225fb99a295425666386d998e2da6b4ffb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-lokern
 * [new ref]         20e0f8225fb99a295425666386d998e2da6b4ffb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 20e0f82 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild