tidy_bytes

# File activesupport/lib/active_support/multibyte/chars.rb, line 636
        def tidy_bytes(string)
          string.split(//u).map do |c|
            c.force_encoding(Encoding::ASCII) if c.respond_to?(:force_encoding)

            if !ActiveSupport::Multibyte::VALID_CHARACTER['UTF-8'].match(c)
              n = c.unpack('C')[0]
              n < 128 ? n.chr :
              n < 160 ? [UCD.cp1252[n] || n].pack('U') :
              n < 192 ? "\xC2" + n.chr : "\xC3" + (n-64).chr
            else
              c
            end
          end.join
        end