$ git clone -n https://src.fedoraproject.org/rpms/R-quantities.git /var/lib/mock/f45-build-6365-348/root/chroot_tmpdir/scmroot/R-quantities
Cloning into '/var/lib/mock/f45-build-6365-348/root/chroot_tmpdir/scmroot/R-quantities'...
$ git fetch origin f6e9229b5a108a2981329b3b99956e9693e74b81:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-quantities
 * [new ref]         f6e9229b5a108a2981329b3b99956e9693e74b81 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f6e9229 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild