Bug Report or Feature Request (mark with an x)

- [x] bug report
- [ ] feature request

Versions.

@angular/cli: 1.1.1
@angular/cli: 1.2.0-beta.1

Repro steps.

• Set "serviceWorker": true for your app in .angular-cli.json
• Create a simple custom ngsw-manifest.json in project root, for example:
  { "push": { "showNotifications": true } }
• Run ng build --prod
• Generated dist/ngsw-manifest.json will contain only static plugin settings, push will be ignored.
• Roll back to CLI 1.0.4 to see the difference

Repo to experiment with

https://github.com/webmaxru/pwa-workshop-angular/tree/step9