consensus.py: Fix typo in Python 3 implementation. - Also, make defensive change to get_consensus_duplex() for safety.   - Use the length of each family instead of one to form the arrays.
consensus.py: Fix typo in Python 3 implementation.
- Also, make defensive change to get_consensus_duplex() for safety.
  - Use the length of each family instead of one to form the arrays.

makrutenko/dunovo,makrutenko/dunovo,makrutenko/dunovo