$ git clone -n https://src.fedoraproject.org/rpms/erlang-hex_core.git /var/lib/mock/f40-build-1769143-24749/root/chroot_tmpdir/scmroot/erlang-hex_core
Cloning into '/var/lib/mock/f40-build-1769143-24749/root/chroot_tmpdir/scmroot/erlang-hex_core'...
$ git fetch origin 6a2fa185b8445c25d7ad9eaa9d85cd9ba7600aa7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/erlang-hex_core
 * [new ref]         6a2fa185b8445c25d7ad9eaa9d85cd9ba7600aa7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6a2fa18 hex_core ver. 0.10.2