title: angular-cli: environment file replacement is broken after switch to webpack (with `ng eject`)
body: <p>I decided to use extended webpack configuration for angular-cli, so I ran command <code>ng eject</code>.</p>
  
  <p>It looks like everything is working except environment file replacement, that is specified in angular-cli.json: </p>
  
  <pre><code>"environmentSource": "environments/environment.ts",
    "environments": {
      "dev": "environments/environment.ts",
      "prod": "environments/environment.prod.ts"
    }
  </code></pre>
  
  <p>Now there is not replacement at all and it always uses "environments/environment.ts" file. </p>
  
  <p>Is there a way to make it work without significant changes for webpack config?</p>
  
  <p>Also created <a href="https://github.com/angular/angular-cli/issues/4907" rel="noreferrer">an issue</a> for angular-cli github project.</p>