$ git clone -n https://src.fedoraproject.org/rpms/R-mAr.git /var/lib/mock/f45-build-6199-347/root/chroot_tmpdir/scmroot/R-mAr
Cloning into '/var/lib/mock/f45-build-6199-347/root/chroot_tmpdir/scmroot/R-mAr'...
$ git fetch origin e5fddd3200451551c57e987ac3de15c4c56018db:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-mAr
 * [new ref]         e5fddd3200451551c57e987ac3de15c4c56018db -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e5fddd3 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild