$ git clone -n https://src.fedoraproject.org/rpms/R-ps.git /var/lib/mock/f42-build-3530686-46321/root/chroot_tmpdir/scmroot/R-ps
Cloning into '/var/lib/mock/f42-build-3530686-46321/root/chroot_tmpdir/scmroot/R-ps'...
$ git fetch origin 5d2529c2e8dd84466e5f1a792e644cda0c3272b2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-ps
 * [new ref]         5d2529c2e8dd84466e5f1a792e644cda0c3272b2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5d2529c R-maint-sig mass rebuild