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This is still an issue on Linux in both 3.4 and 3.7 even when using io.open() as suggested by @vstinner:
>>> import io, os, fcntl
>>> r, w = os.pipe()
>>> fcntl(r, fcntl.F_SETFL, os.O_NONBLOCK)
0
>>> stream = io.open(r, 'rt')
>>> stream
<_io.TextIOWrapper name=X mode='rt' encoding='UTF-8'>
>>> stream.buffer
<_io.BufferedReader name=X>
>>> print(repr(stream.buffer.read()))
None
>>> stream.read()
Traceback (most recent call last):
 ...
 File ".../python3.7/codecs.py"..., in decode
 data = self.buffer + input
TypeError: can't concat NoneType to bytes
The error is present in at least 3.4 up to 3.7 where the underlying buffer.read() returns None which is not handled by the TextIOStream.