emberjs/ember.js — pull request #9767 by martinmaillard (2014-12-01 12:15:16+00:00)
Title: Use Ember.set to set controller in Route.setup

Under specific circumstances that I could not identify, the following error is raised:

Error while processing route: [route-name] Assertion Failed: You must use Ember.set() to set the `controller` property (of [route]) to `[controller]`.

This change fixes the error.