He’s back.

Have the same issue after an system update on arch a few day ago. Today update had it fixed.

Seem like an issue with glibc.

Yeah, from what I understand. If it an one-off encounter (annihilate each other), then tit for tat will lose most of the times. That is original version Prisoner’s dilemma and the answer for that version is you all should betray each other. When the scenario is not an one-off encounter but a repeated once then tit for tat will win most of the times.