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.