Merged revisions 79278,79280 via svnmerge from

Merged revisions 79278,79280 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

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  r79278 | victor.stinner | 2010-03-22 13:24:37 +0100 (lun., 22 mars 2010) | 2 lines

  Issue #1583863: An unicode subclass can now override the __str__ method
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  r79280 | victor.stinner | 2010-03-22 13:36:28 +0100 (lun., 22 mars 2010) | 5 lines

  Fix the NEWS about my last commit: an unicode subclass can now override the
  __unicode__ method (and not the __str__ method).

  Simplify also the testcase.
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