title: Rails 3 rendering template missing without file ending
body: <p>I have an action in my controller as below:</p>
  
  <pre><code> def show
      @post = Post.find_by_setitle(params[:setitle])
  
      if !@post
        render 'error_pages/404'
        return
      end
  
      respond_to do |format|
        format.html
      end
    end
  </code></pre>
  
  <p>If the <code>render error_pages/404</code> I get a template missing. Switching it to <code>render error_pages/404.haml.html</code> works fine.</p>
  
  <p>Why is this?</p>
  
  <p>N.B. There is no actual error_pages controller or model. Just a convenient place to keep them.</p>
  
  <p>Edit: I'm using mongoid and hence don't have access to ActiveRecord. Controller base can't be looking for a particular ActiveRecord exception?</p>