ember-concurrency cancel problem

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

router.js

import Ember from 'ember';
import config from './config/environment';

const Router = Ember.Router.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
});

export default Router;

routes.index.js

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

export default Ember.Route.extend({
  performTask: task(function * () {
  	yield timeout(2000);
  }) 
});

templates.application.hbs

<button type="button" onclick={{perform (route-task 'performTask')}}>
	{{#if (get (route-task 'performTask') 'isIdle')}} 
		Perform Task
	{{else}} 
		Loading...
	{{/if}}
</button> 

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": "latest", 
    "ember-route-task-helper": "latest"
  }
}