$ git clone -n https://src.fedoraproject.org/rpms/R-httpuv.git /var/lib/mock/f38-build-side-42-init-devel-640153-26389/root/chroot_tmpdir/scmroot/R-httpuv
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-640153-26389/root/chroot_tmpdir/scmroot/R-httpuv'...
$ git fetch origin b766dfb209b2e7da54d61f25766bd45c47c805e0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-httpuv
 * [new ref]         b766dfb209b2e7da54d61f25766bd45c47c805e0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b766dfb update to 1.6.9