require doesn't trigger deadlock

[tekumara]

IIUC this should trigger a deadlock, when Human.Input runs a second time, but it doesn't?

---
deadlock_detection: true
action_options:
    Human.Input:
        max_actions: 2
        max_concurrent_actions: 1
---

role Human:
  action Init:
    self.history = []

  action Input:
    input = None
    response = self.history[-1] if self.history else None
    if not response:
      input = ("Human","a")

    require input
    self.history.append(input)
    pass    # ... more happens here ...

action Init:
  h = Human()