RouterService: rootURL inconsistencies

controllers.application.js

import Controller from '@ember/controller';
import { inject as service } from '@ember/service';
import { computed } from '@ember/object';

export default Controller.extend({
  router: service(),
  
  urlFor: computed(function() {
    return this.router.urlFor(this.router.currentRouteName);
  }),
  
  actions: {
    transitionTo(url) {
      this.router.transitionTo(url);
    }
  }
});

router.js

import EmberRouter from '@ember/routing/router';
import config from './config/environment';

const Router = EmberRouter.extend({
  location: 'none',
  rootURL: '/some/prefix/'
});

Router.map(function() {
});

export default Router;

templates.application.hbs

<dl>
  <dt>currentRouteName</dt>
  <dd>'{{router.currentRouteName}}'</dd>
  
  <dt>currentURL</dt>
  <dd>'{{router.currentURL}}'</dd>
  
  <dt>urlFor(currentRouteName)</dt>
  <dd>'{{urlFor}}'</dd>
  
  <dt>rootURL</dt>
  <dd>'{{router.rootURL}}'</dd>
</dl>

Works:

<button {{action "transitionTo" currentURL}}>
  Navigate to currentURL: '{{currentURL}}'
</button>

<br>

Works:

<button {{action "transitionTo" "/"}}>
  Navigate to: '/'
</button>

<br>

Broken:

<button {{action "transitionTo" urlFor}}>
  Navigate to urlFor(currentRouteName): '{{urlFor}}'
</button>

twiddle.json

{
  "version": "0.15.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.2.2",
    "ember-template-compiler": "3.2.2",
    "ember-testing": "3.2.2"
  },
  "addons": {
    "ember-data": "3.2.0"
  }
}