$ git clone -n https://src.fedoraproject.org/rpms/R-reticulate.git /var/lib/mock/f42-build-side-110318-58926197-6569309/root/chroot_tmpdir/scmroot/R-reticulate
Cloning into '/var/lib/mock/f42-build-side-110318-58926197-6569309/root/chroot_tmpdir/scmroot/R-reticulate'...
$ git fetch origin dab2506fb285d0b493db6aeca1ce4e31154655c1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-reticulate
 * [new ref]         dab2506fb285d0b493db6aeca1ce4e31154655c1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dab2506 Fix Rf_error definition