title: No route matches although there is one in rake routes
body: <p>I get strange <code>ActionController::RoutingError: No route matches</code>. The route can be generated:</p>
  
  <pre><code>&gt; r = Rails.application.routes
  &gt; r.generate controller: :items, action: :index, user_id:1
    =&gt; ["/users/1/items", {}] 
  </code></pre>
  
  <p>And it is in the <code>rake routes</code>:</p>
  
  <pre><code>$ rake routes
       user_items GET    /users/:user_id/items(.:format)          items#index
                  POST   /users/:user_id/items(.:format)          items#create
    new_user_item GET    /users/:user_id/items/new(.:format)      items#new
   edit_user_item GET    /users/:user_id/items/:id/edit(.:format) items#edit
        user_item GET    /users/:user_id/items/:id(.:format)      items#show
                  PUT    /users/:user_id/items/:id(.:format)      items#update
                  DELETE /users/:user_id/items/:id(.:format)      items#destroy
  (...)
  </code></pre>
  
  <p>But I it's not recognized:</p>
  
  <pre><code>r.recognize_path "/users/1/items"
  ActionController::RoutingError: No route matches "/users/1/items"
  </code></pre>
  
  <p>My <code>routes.rb</code>:</p>
  
  <pre><code>Sumo2::Application.routes.draw do
    resources :users do
      resources :items
    end
    (...)
  end
  </code></pre>
  
  <p>Any ideas?</p>