Merged revisions 82766 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/branches/py3k

Since 'purge' is an API change, modified it to be _purge for 3.1
and deleted the doc update.

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  r82766 | r.david.murray | 2010-07-10 09:52:13 -0400 (Sat, 10 Jul 2010) | 5 lines

  Fix 'refleak' introduced by fnmatch cache purge tests.

  This introduces a 'purge' function for the fnmatch module analogous
  to the 'purge' function in the re module.
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