$ git clone -n https://src.fedoraproject.org/rpms/R-S4Vectors.git /var/lib/mock/f45-build-5960-345/root/chroot_tmpdir/scmroot/R-S4Vectors
Cloning into '/var/lib/mock/f45-build-5960-345/root/chroot_tmpdir/scmroot/R-S4Vectors'...
$ git fetch origin 7af11ed61b09a7e5c96689d139ef7f145f8892f7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-S4Vectors
 * [new ref]         7af11ed61b09a7e5c96689d139ef7f145f8892f7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7af11ed Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild