$ git clone -n https://src.fedoraproject.org/rpms/R-yaml.git /var/lib/mock/f38-build-724033-99309/root/chroot_tmpdir/scmroot/R-yaml
Cloning into '/var/lib/mock/f38-build-724033-99309/root/chroot_tmpdir/scmroot/R-yaml'...
$ git fetch origin 4ff6278822a0cd56a4e1fdce092d0fe18c57f50a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-yaml
 * [new ref]         4ff6278822a0cd56a4e1fdce092d0fe18c57f50a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4ff6278 R-maint-sig mass rebuild