polymorphic_url gives incorrect url for :has_one nested resource

With a nested :has_one resource

  map.resources :articles, :has_one => :response

a call to polymorphic_url

  polymorphic_url([@article, @response])

should result in a call to:

  article_response_url(@article)
  # url is then: articles/:article_id/response

Currently the following is called, resulting in the incorrect id being used in the URL:

  article_response_url(@article, @response)
  # url is then incorrect: articles/:response_id/response

Below is one possible test and solution.

In rails/actionpack/test/controller/polymorphic_routes_test.rb

def test_path_with_has_one_nested
  @response.save
  Article.expects(:respond_to?).
      with(:reflect_on_association).
      returns(true)

  has_one = mock('association',
      :macro =>:has_one)
  Article.expects(:reflect_on_association).
      with(:response).returns(has_one)

  expects(:article_response_url).with(@article)
  polymorphic_url([@article, @response])
end

In rails/actionpack/lib/action_controller/polymorphic_routes.rb

def handle_has_one_nested(args)
  if args.size == 2
    model_class = args.first.class
    if model_class.respond_to?(:reflect_on_association)
      second_model_class = args.last.class
      association_name = second_model_class.name.tableize.singularize.to_sym
      association = model_class.reflect_on_association(association_name)
      if association && association.macro == :has_one
        args.pop
      end
    end
  end
  args
end

# call above method in existing polymorphic_url:

def polymorphic_url(record_or_hash_or_array, options = {})
  if record_or_hash_or_array.kind_of?(Array)
    record_or_hash_or_array = record_or_hash_or_array.dup
  end

  record    = extract_record(record_or_hash_or_array)
  format    = extract_format(record_or_hash_or_array, options)
  namespace = extract_namespace(record_or_hash_or_array)

  args = case record_or_hash_or_array
    when Hash;  [ record_or_hash_or_array ]
    when Array; record_or_hash_or_array.dup
    else        [ record_or_hash_or_array ]
  end

  inflection =
    case
    when options[:action].to_s == "new"
      args.pop
      :singular
    when record.respond_to?(:new_record?) && record.new_record?
      args.pop
      :plural
    else
      :singular
    end

  args = handle_has_one_nested(args) # ** <- Add here **

  args.delete_if {|arg| arg.is_a?(Symbol) || arg.is_a?(String)}
  args << format if format

  named_route = build_named_route_call(record_or_hash_or_array, namespace, inflection, options)

  url_options = options.except(:action, :routing_type, :format, :association)
  unless url_options.empty?
    args.last.kind_of?(Hash) ? args.last.merge!(url_options) : args << url_options
  end

  __send__(named_route, *args)
end