Merged revisions 74336 via svnmerge from

Merged revisions 74336 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

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  r74336 | antoine.pitrou | 2009-08-06 22:18:29 +0200 (jeu., 06 août 2009) | 8 lines

  Issue #6629: Fix a data corruption issue in the new `io` package, which could
  occur when writing to a BufferedRandom object (e.g. a file opened in "rb+" or
  "wb+" mode) after having buffered a certain amount of data for reading. This
  bug was not present in the pure Python implementation.

  Yes, this is a serious issue.
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