$ git clone -n https://src.fedoraproject.org/rpms/erlang-hex_core.git /var/lib/mock/f41-build-735308-13228/root/chroot_tmpdir/scmroot/erlang-hex_core
Cloning into '/var/lib/mock/f41-build-735308-13228/root/chroot_tmpdir/scmroot/erlang-hex_core'...
$ git fetch origin ed7d8dd5cb012341233aa8561cdbcff4deba5cb2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/erlang-hex_core
 * [new ref]         ed7d8dd5cb012341233aa8561cdbcff4deba5cb2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ed7d8dd Fix FTBFS with Rebar3