$ git clone -n https://src.fedoraproject.org/rpms/rust2rpm-helper.git /var/lib/mock/f45-build-46385-834/root/chroot_tmpdir/scmroot/rust2rpm-helper
Cloning into '/var/lib/mock/f45-build-46385-834/root/chroot_tmpdir/scmroot/rust2rpm-helper'...
$ git fetch origin 7b0da3894d72683fb8c766876cb8ea539326f56c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust2rpm-helper
 * [new ref]         7b0da3894d72683fb8c766876cb8ea539326f56c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7b0da38 Update to version 0.2.0; Fixes RHBZ#2509868