# File lib/merb-core/dispatch/request_parsers.rb, line 204
    def self.unescape(s, encoding = nil)
      s = s.tr('+', ' ').gsub(/((?:%[0-9a-fA-F]{2})+)/n){
        [$1.delete('%')].pack('H*')
      }
      if RUBY_VERSION >= '1.9'
        encoding ||= Encoding.default_internal
        s.force_encoding(encoding) if encoding
      end
      s
    end