Merged revisions 86981,86984 via svnmerge from

Merged revisions 86981,86984 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/branches/py3k

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  r86981 | antoine.pitrou | 2010-12-03 19:41:39 +0100 (ven., 03 déc. 2010) | 5 lines

  Issue #10478: Reentrant calls inside buffered IO objects (for example by
  way of a signal handler) now raise a RuntimeError instead of freezing the
  current process.
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  r86984 | antoine.pitrou | 2010-12-03 20:14:17 +0100 (ven., 03 déc. 2010) | 3 lines

  Add an "advanced topics" section to the io doc.
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