$ git clone -n https://src.fedoraproject.org/rpms/R-corpus.git /var/lib/mock/f38-build-724974-99530/root/chroot_tmpdir/scmroot/R-corpus
Cloning into '/var/lib/mock/f38-build-724974-99530/root/chroot_tmpdir/scmroot/R-corpus'...
$ git fetch origin df504b1ca0c72184f42e17a3c060e3ed9b6ece4d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-corpus
 * [new ref]         df504b1ca0c72184f42e17a3c060e3ed9b6ece4d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at df504b1 Ignore vignettes