localized_rescue.rb

# actionpack/lib/action_controller/rescue.rb 
#
module ActionController
  class Base

    protected
      # Attempts to render a static localized error page based on the <tt>status_code</tt>
      # thrown, or just return headers if no such files exists. For example, if a 500 error
      # is being handled Rails will first attempt to render the file based on the current
      # locale such as <tt>public/500.pt-BR.html</tt>. If it does not exist, attempts to 
      # render <tt>public/500.html</tt>. If the files doesn't exist, the body of the response
      # will be left empty.
      #
      def render_optional_error_file(status_code)
        status = interpret_status(status_code)
        locale_path = "#{Rails.public_path}/#{status[0,3]}.#{I18n.locale}.html" if I18n.locale
        path = "#{Rails.public_path}/#{status[0,3]}.html"

        if locale_path && File.exist?(locale_path)
          render :file => locale_path, :status => status, :content_type => Mime::HTML
        elsif File.exist?(path)
          render :file => path, :status => status, :content_type => Mime::HTML
        else
          head status
        end
      end

  end
end