$ git clone -n https://src.fedoraproject.org/rpms/rust2rpm-helper.git /var/lib/mock/f41-build-861532-169814/root/chroot_tmpdir/scmroot/rust2rpm-helper
Cloning into '/var/lib/mock/f41-build-861532-169814/root/chroot_tmpdir/scmroot/rust2rpm-helper'...
$ git fetch origin 8975b6ab1165be745fd9dfd3cbd1e7732b7d2192:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust2rpm-helper
 * [new ref]         8975b6ab1165be745fd9dfd3cbd1e7732b7d2192 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8975b6a Update to version 0.1.6; Fixes RHBZ#2318767