How to build production environment with canary flags?

I would like to use one of canary flags currently available in ember-data 2.4.0-beta.2. When I use ember serve it works as expected. But with ember build --prod it throws error on code that requires that flag. I assume I have to enable it somewhere but didn't have any luck finding any documentation for it.

// I added flag into environment and made sure that it is not overridden on production
EmberENV: {
  FEATURES: {
    'ds-references': true
  }
},