How to namespace routes in RefineryCMS Engine to a resource outside of refinery.

engine_routes.rb

Refinery::Core::Engine.routes.draw do

  # Frontend routes
  resources :core_topics do
    namespace :articles, :path => '/articles' do
      resources :articles, :path => '', :only => [:index, :show]
    end
  end

  # Admin routes
  namespace :articles, :path => '' do
    namespace :admin, :path => 'refinery' do
      resources :articles, :except => :show do
        collection do
          post :update_positions
        end
      end
    end
  end

end

routes.rb

RefinerySpree::Application.routes.draw do
  resources :core_topics
  mount Refinery::Core::Engine, :at => '/'
end