$ git clone -n https://src.fedoraproject.org/rpms/R-vctrs.git /var/lib/mock/f38-build-side-42-init-devel-962406-28791/root/chroot_tmpdir/scmroot/R-vctrs
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-962406-28791/root/chroot_tmpdir/scmroot/R-vctrs'...
$ git fetch origin e86629f6890f9a004eb0b86ba4bd56617a43e817:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-vctrs
 * [new ref]         e86629f6890f9a004eb0b86ba4bd56617a43e817 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e86629f update to 0.5.2