Third to last example is now marked as a test, but I can't actually test

Third to last example is now marked as a test, but I can't actually test
it yet since sphinx can't run the doctests using python3.

Merged revisions 72038 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

........
  r72038 | r.david.murray | 2009-04-27 13:22:36 -0400 (Mon, 27 Apr 2009) | 8 lines

  Make sys.xxx variable references into links, note that print_last only
  works when an exception gets to the interactive prompt, and update the
  examples after testing.  The last one is now a valid Sphinx doctest,
  but of the preceding two one can't be made a doctest and the other one
  I'm postponing to 3.x because sphinx handles doctests as Unicode strings
  and that makes the 2.x output confusing.
........