# File lib/rack/utils.rb, line 660
    def clean_path_info(path_info)
      parts = path_info.split PATH_SEPS

      clean = []

      parts.each do |part|
        next if part.empty? || part == '.'
        part == '..' ? clean.pop : clean << part
      end

      clean.unshift '/' if parts.empty? || parts.first.empty?

      ::File.join(*clean)
    end