Auto-switching between prod and dev Ember version. The JS files in the custom-ember directory are symlinks to ../../../ember.js/dist/ember.prod.js etc., where ember.js is a submodule.

custom-ember.js.erb

<% require_asset 'custom-ember/handlebars' %>
<% if Rails.env.production? %>
  <% require_asset 'custom-ember/ember.prod' %>
  <% require_asset 'custom-ember/ember-data.prod' %>
<% else %>
  <% require_asset 'custom-ember/ember' %>
  <% require_asset 'custom-ember/ember-data' %>
<% end %>