cache_update_path

# File lib/rubygems/remote_fetcher.rb, line 295
  def cache_update_path(uri, path = nil, update = true)
    mtime = path && File.stat(path).mtime rescue nil

    data = fetch_path(uri, mtime)

    if data == nil # indicates the server returned 304 Not Modified
      return Gem.read_binary(path)
    end

    if update and path
      Gem.write_binary(path, data)
    end

    data
  end