Unicode confusion

If I follow this -- and it's very nicely spelled out -- then it *seems* to follow that the fact that these lines

  unicodeVowels = u"[ae\xe8iouy]+"
  uVowels = sre.compile(unicodeVowels)

produce a regex pattern that successfully matches e-with-grave in text files on both Mac and Windows -- in the absence of any mystring.encode('utf8') line! -- is unreliable accident. Is that right?

Charles Hartman