CP setter without return value misbehaves

controllers.application.js

import Ember from 'ember';
const { computed } = Ember;

export default Ember.Controller.extend({
  goldenRatioWidth: computed('height', {
    get(key) {
      return this.get('height') * 1.618;
    },
    set(_, value) {
      this.set('height', value / 1.618);
      // Try commenting out the return statement...
      return value;
    }
  }),
  
  height: 100
});

templates.application.hbs

<p>Width: {{input value=goldenRatioWidth}}</p>
<p>Height: {{input value=height}}</p>

twiddle.json

{
  "version": "0.4.0",
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.5/ember.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/1.13.5/ember-data.js"
  }
}