$ git clone -n https://src.fedoraproject.org/rpms/erlang-proper.git /var/lib/mock/f40-build-1210992-22568/root/chroot_tmpdir/scmroot/erlang-proper
Cloning into '/var/lib/mock/f40-build-1210992-22568/root/chroot_tmpdir/scmroot/erlang-proper'...
$ git fetch origin dc9eb8ce7c8a3d4f49499caf90bb0b41053207a0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/erlang-proper
 * [new ref]         dc9eb8ce7c8a3d4f49499caf90bb0b41053207a0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dc9eb8c Fix FTBFS with Rebar3