fix __bytes__ handling here in py3x

Merged revisions 76395 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

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  r76395 | benjamin.peterson | 2009-11-18 21:00:02 -0600 (Wed, 18 Nov 2009) | 1 line

  #5037 proxy __unicode__ correctly
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