$ git clone -n https://src.fedoraproject.org/rpms/R-kernlab.git /var/lib/mock/f45-build-6204-347/root/chroot_tmpdir/scmroot/R-kernlab
Cloning into '/var/lib/mock/f45-build-6204-347/root/chroot_tmpdir/scmroot/R-kernlab'...
$ git fetch origin 61b4945ecbe5ef6628d9bee93a4fd6cccce7f7bd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-kernlab
 * [new ref]         61b4945ecbe5ef6628d9bee93a4fd6cccce7f7bd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 61b4945 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild