$ git clone -n https://src.fedoraproject.org/rpms/R-chron.git /var/lib/mock/f45-build-6008-345/root/chroot_tmpdir/scmroot/R-chron
Cloning into '/var/lib/mock/f45-build-6008-345/root/chroot_tmpdir/scmroot/R-chron'...
$ git fetch origin d41a25859da1d38a69703e05d9a2f80dbb632d6e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-chron
 * [new ref]         d41a25859da1d38a69703e05d9a2f80dbb632d6e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d41a258 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild