I pulled this down for a more thorough code review today, and realized that I'm not clear what the actual acceptance criteria is here. From the description, I would expect garbled tally output for STV poll tallies, but the output from master seems fine?
I double checked in the cli:
sh $ docker compose exec mediawiki bash -c "php extensions/SecurePoll/cli/tally.php --name 'stv 2'"