os.{read,write} isn't handled by futurize; affected by bytes/unicode str change in python 3

[ngie-eign]

As was brought to my attention that os.{read,write} only handles interpolation to/from bytes in python 3.

While using os.read and os.write on python 2 works "out-of-the-box" on with str since the type is bytes-based, it doesn't on python 3. Example:

>>> import os
>>> fd = os.open(os.devnull, os.O_WRONLY)
>>> os.write(fd, "foobar")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: a bytes-like object is required, not 'str'

It would have been helpful if a built-in alias had been installed for str to match the new behavior, or something similar had been done using a backport from the io module.

Note: I am aware that the number of future releases with new code is decreasing over time: this is mainly being provided as documentation, since this caveat wasn't mentioned anywhere obvious I noted and there are some orgs who are still working on their python 2-3 conversions.