Merged revisions 65787 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

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  r65787 | brett.cannon | 2008-08-17 15:10:11 -0700 (Sun, 17 Aug 2008) | 3 lines

  Remove imports of 'warnings' that are no longer needed in dummy_thread,
  filecmp, and shelve.
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