With 2.7 and 3.4 (same for 32- and 64-bit):

>>> f = open('test.bin', 'wb')
>>> f.write(b' ' * (1024*1024*100))
104857600
>>> f.close()
>>> import os
>>> os.stat('test.bin').st_size
104857600

The linked KB only applies to VS 2003 and VS 2005 (VC7 and VC8), so I'm not entirely surprised that this doesn't repro with VC9 or VC10.

For the subprocess case (on 3.4):

>>> import sys, subprocess
>>> p=subprocess.Popen([sys.executable, '-c', 'print(len(input()))'], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
>>> p.communicate(b' ' * (1024*1024*100))
(b'104857600\r\n', b'')

I'm inclined to close this as no repro unless we get an actual repro.