So, here's one big patch. I have updated the behavior of close(), so that 

> The profile tests often fail when io.py changes because they happen to
> depend on "golden output" which includes line numbers of code in io.py
> that happens to be traced during the test. 

Yes, I knew that. But, how can I fix the test so that it passes even if
_bytesio is not available?

Oh, one more thing. In the misc fixes for io.py, I added a checkClosed
in IOBase.readline(). As a side-effect, this make __next__ raises a
ValueError, instead of StopIteration. Is that correct?  

>>> f = open("load.py")
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>>> next(f)
'import sys\n'
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>>> f.close()
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>>> next(f)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/alex/src/python.org/py3k/Lib/io.py", line 1440, in __next__
    line = self.readline()
  File "/home/alex/src/python.org/py3k/Lib/io.py", line 1449, in readline
    raise ValueError("read from closed file")
ValueError: read from closed file
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