message: Make sure to only signal if a ticket was found.
diff: @@ -310,9 +310,10 @@ describe("Semaphore", function() {
  case 1:
  {
  var ticket1 = tickets.shift();
  - if (ticket1)
  + if (ticket1) {
  ++expectedAcquired;
  sem.signal();
  + }
  break;
  }
  case 2:
  