$ git clone -n https://src.fedoraproject.org/rpms/erlang-relx.git /var/lib/mock/f40-build-1817409-24911/root/chroot_tmpdir/scmroot/erlang-relx
Cloning into '/var/lib/mock/f40-build-1817409-24911/root/chroot_tmpdir/scmroot/erlang-relx'...
$ git fetch origin 284753d0eb0e6119b2c6c1513e9700f19c781e82:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/erlang-relx
 * [new ref]         284753d0eb0e6119b2c6c1513e9700f19c781e82 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 284753d relx ver. 4.9.0