class Gem::Request

def fetch
  request = @request_class.new @uri.request_uri
  unless @uri.nil? || @uri.user.nil? || @uri.user.empty?
    request.basic_auth Gem::UriFormatter.new(@uri.user).unescape,
                       Gem::UriFormatter.new(@uri.password).unescape
  end
  request.add_field "User-Agent", @user_agent
  request.add_field "Connection", "keep-alive"
  request.add_field "Keep-Alive", "30"
  if @last_modified
    require "time"
    request.add_field "If-Modified-Since", @last_modified.httpdate
  end
  yield request if block_given?
  perform_request request
end