Merged revisions 55588-55630 via svnmerge from

Merged revisions 55588-55630 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/branches/p3yk

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  r55598 | neal.norwitz | 2007-05-26 10:44:02 +0800 (Sat, 26 May 2007) | 1 line

  Fix refleak on infinite recursion
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  r55599 | neal.norwitz | 2007-05-26 10:47:45 +0800 (Sat, 26 May 2007) | 1 line

  Add news entry about overidding isinstance/issubclass (PEP 3119)
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  r55629 | brett.cannon | 2007-05-29 08:06:59 +0800 (Tue, 29 May 2007) | 3 lines

  Delete the cstubs module.  Used as input to Modules/cgen.py to generate the gl
  module which has already been removed.
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