Ember Concurrnency LastSuccessful gotcha

controllers.application.js

import Ember from 'ember';
import {task, timeout} from 'ember-concurrency';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  holdAndWait: task(function*(millis, value){
    yield timeout(millis);
    return value;
  }),
  
  init(){
    let holder = this.get("holdAndWait");
    holder.perform(2000, "first");
    holder.perform(1000, "second");
  }
  
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{#if holdAndWait.lastSuccessful}}
	<h3>{{holdAndWait.lastSuccessful.value}}</h3>
  <h4>{{if (eq holdAndWait.lastSuccessful.value "first") ":(" ":)"}}</h4>
{{/if}}
<br>
<br>

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1",
    "ember-concurrency": "0.7.19",
    "ember-truth-helpers": "1.3.0"
  }
}