timeout exception after update to 1.0.0 when using timeoutExitValue=0

[yanns]

After having update from 1.0.0-M1 to 1.0.0, I receive timeout exception when using js-engine.

The change:
yanns/play-react@aa1098d#diff-fdc3abdfd754eeb24090dbd90aeec2ceR12

Error:

[application-akka.actor.default-dispatcher-6] [akka://application/user/engine-196] Message [akka.actor.Terminated] from Actor[akka://application/user/engine-196/stderr#-264922344] to Actor[akka://application/user/engine-196#1741387420] was not delivered. [2] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'

[yanns]

It works again when I remove the timeoutExitValue = 0 argument
yanns/play-react@aa1098d#diff-2bc81ddbaac9248c65583b4697ee54faR80

[yanns]

A test to reproduce the error:

      val system = ActorSystem()

      val f = new File(classOf[TriremeSpec].getResource("test-node.js").toURI)
      implicit val timeout = Timeout(5000L, TimeUnit.MILLISECONDS)

      val engine1 = system.actorOf(Trireme.props(), s"trireme-${UUID.randomUUID().toString}")
      val futureResult1 = (engine1 ? Engine.ExecuteJs(f, immutable.Seq("999"), timeout.duration, 0)).mapTo[JsExecutionResult]

      val engine2 = system.actorOf(Trireme.props(), s"trireme-${UUID.randomUUID().toString}")
      val futureResult2 = (engine2 ? Engine.ExecuteJs(f, immutable.Seq("999"), timeout.duration, 0)).mapTo[JsExecutionResult]

      val result1 = Await.result(futureResult1, timeout.duration)
      new String(result1.output.toArray, "UTF-8").trim must_== "999"
      new String(result1.error.toArray, "UTF-8").trim must_== ""

      val result2 = Await.result(futureResult2, timeout.duration)
      new String(result2.output.toArray, "UTF-8").trim must_== "999"
      new String(result2.error.toArray, "UTF-8").trim must_== ""

(to add in TriremeSpec)

The error does not occur every time.