possible ms02 bug and how to fix it.

update on 20180202: it turns out the input pairs of network contain redundant pairs. So, input data need to be checked for consistency by a switch, such as "-input-check 1"

It is possible that recursive call return pairs that already existed in previous iterations, in recursive implementation.

This may explain why large network permutation give slightly different random networks.

One way to fix this is to do book-keeping on the entire networks (instead of a small chunk using recursive definitions). This may be implemented in a separate functional call, breaking self-pairing and reassignment partners.