old_contents: import run from 'ember-runloop';
  
  export default function destroyApp(application) {
      run(application, 'destroy');
  }
  
new_contents: import run from 'ember-runloop';
  
  export default function destroyApp(application) {
      // this is required to fix "second Pretender instance" warnings
      if (server) {
          server.shutdown();
      }
  
      run(application, 'destroy');
  }
  
subject: add manual pretender shutdown to fix acceptance tests (#342)