$ git clone -n https://src.fedoraproject.org/rpms/mbuffer.git /var/lib/mock/f45-build-18160-510/root/chroot_tmpdir/scmroot/mbuffer
Cloning into '/var/lib/mock/f45-build-18160-510/root/chroot_tmpdir/scmroot/mbuffer'...
$ git fetch origin c1c8e9154f91e8d7b7f56296cf90dc5dda7efc7a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mbuffer
 * [new ref]         c1c8e9154f91e8d7b7f56296cf90dc5dda7efc7a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c1c8e91 drop ix86 support