Peter, it seems that detach is relatively new (3.1) likely the code samples and suggestions that I had found to cure the problem predate that.  While I haven't yet tried detach, your code doesn't seem to modify stdin, so are you suggesting, really...

   sys.stdin = sys.stdin.detach()

or maybe

   if hasattr( sys.stdin, 'detach'):
        sys.stdin = sys.stdin.detach()

On the other hand, if detach, coded as above, is equivalent to 

   if hasattr( sys.stdin, 'buffer'):
        sys.stdin = sys.stdin.buffer

then I wonder why it was added.  So maybe I'm missing something in reading the documentation you pointed at, and also that at http://docs.python.org/py3k/library/io.html#io.TextIOBase.detach
both of which seem to be well-documented if you already have an clear understanding of the layers in the IO subsystem, but perhaps not so well-documented if you don't yet (and I don't).

But then you referred to the platform-dependent stuff... I don't see anything in the documentation for detach() that implies that it also makes the adjustments needed on Windows to the C-runtime, which is what the platform-dependent stuff I suggested does... if it does, great, but a bit more documentation would help in understanding that.  And if it does, maybe that is the difference between the two code fragments in this comment?  I would have to experiment to find out, and am not in a position to do that this moment.