$ git clone -n https://src.fedoraproject.org/rpms/rpmrebuild.git /var/lib/mock/f42-build-side-1-3539454-46565/root/chroot_tmpdir/scmroot/rpmrebuild
Cloning into '/var/lib/mock/f42-build-side-1-3539454-46565/root/chroot_tmpdir/scmroot/rpmrebuild'...
$ git fetch origin 24d42a1031e113139e5b7976bcb785e687353d95:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rpmrebuild
 * [new ref]         24d42a1031e113139e5b7976bcb785e687353d95 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 24d42a1 Simplify %files list