$ git clone -n https://src.fedoraproject.org/rpms/R-Rcpp.git /var/lib/mock/f45-build-5899-345/root/chroot_tmpdir/scmroot/R-Rcpp
Cloning into '/var/lib/mock/f45-build-5899-345/root/chroot_tmpdir/scmroot/R-Rcpp'...
$ git fetch origin 4994660bba5d21985ca998682ea2db9e43ef808c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-Rcpp
 * [new ref]         4994660bba5d21985ca998682ea2db9e43ef808c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4994660 Update to 1.1.2