$ git clone -n https://src.fedoraproject.org/rpms/R-gert.git /var/lib/mock/f38-build-side-42-init-devel-946023-28778/root/chroot_tmpdir/scmroot/R-gert
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-946023-28778/root/chroot_tmpdir/scmroot/R-gert'...
$ git fetch origin 0a3ae19ffd0892882d0f52cd11ed0d8647a43125:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-gert
 * [new ref]         0a3ae19ffd0892882d0f52cd11ed0d8647a43125 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0a3ae19 Rebuild for libgit2 1.6.x