$ git clone -n https://src.fedoraproject.org/rpms/R-diffobj.git /var/lib/mock/f45-build-6091-346/root/chroot_tmpdir/scmroot/R-diffobj
Cloning into '/var/lib/mock/f45-build-6091-346/root/chroot_tmpdir/scmroot/R-diffobj'...
$ git fetch origin fb616867ab1fb3b335e561ec8c02ff7fcfc03222:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-diffobj
 * [new ref]         fb616867ab1fb3b335e561ec8c02ff7fcfc03222 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fb61686 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild