Merged revisions 68890 via svnmerge from

Merged revisions 68890 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

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  r68890 | mark.dickinson | 2009-01-24 15:27:44 +0000 (Sat, 24 Jan 2009) | 6 lines

  Issue #4393: fix 3 classes of potential portability problems in longobject.c:
   - fix some places where counters into ob_digit were declared as
     int instead of Py_ssize_t
   - add (twodigit) casts where necessary
   - fix code in _PyLong_AsByteArray that uses << on negative values
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