$ git clone -n https://src.fedoraproject.org/rpms/mmapper.git /var/lib/mock/f40-build-2613427-64068/root/chroot_tmpdir/scmroot/mmapper
Cloning into '/var/lib/mock/f40-build-2613427-64068/root/chroot_tmpdir/scmroot/mmapper'...
$ git fetch origin 52ce77c19101b43dc8a5ab28a03112cdede33db9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mmapper
 * [new ref]         52ce77c19101b43dc8a5ab28a03112cdede33db9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 52ce77c ExcludeArch i686 for https://fedoraproject.org/wiki/Changes/EncourageI686LeafRemoval