Merged revisions 79878-79880 via svnmerge from

Merged revisions 79878-79880 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

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  r79878 | philip.jenvey | 2010-04-06 16:24:45 -0700 (Tue, 06 Apr 2010) | 4 lines

  #7301: add the environment variable $PYTHONWARNINGS to supplement the -W
  command line option
  patch from Brian Curtin
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  r79879 | benjamin.peterson | 2010-04-06 16:32:27 -0700 (Tue, 06 Apr 2010) | 1 line

  tell people to update python.man, too
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  r79880 | philip.jenvey | 2010-04-06 16:38:57 -0700 (Tue, 06 Apr 2010) | 1 line

  document new PYTHONWARNINGS env var
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