[docs] [issue1643712] Emphasize buffering issues when sys.stdin is used

[Mark Lawrence]

Mark Lawrence <breamoreboy at yahoo.co.uk> added the comment:

Please note update to #1633941

----------
nosy: +BreamoreBoy

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue1643712>
_______________________________________