to_plain_segments

# File actionpack/lib/action_controller/routing/recognition_optimisation.rb, line 147
      def to_plain_segments(str)
        str = str.dup
        str.sub!(/^\/+/,'')
        str.sub!(/\/+$/,'')
        segments = str.split(/\.[^\/]+\/+|\/+|\.[^\/]+\Z/) # cut off ".format" also
        segments << nil
        segments
      end