Update docstrings w.r.t. subprocess2.

subprocess2.py

 # coding=utf8
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 """Collection of subprocess wrapper functions.
 
 In theory you shouldn't need anything else in subprocess, or this module failed.
 """
 
 from __future__ import with_statement
@@ skipping 114 matching lines @@
   env = env.copy()
   def fix_lang(name):
     if not is_english(name):
       env[name] = 'en_US.UTF-8'
   fix_lang('LANG')
   fix_lang('LANGUAGE')
   return env
 
 
 def Popen(args, **kwargs):
-  """Wraps subprocess.Popen().
+  """Wraps subprocess.Popen() with various workarounds.
 
   Returns a subprocess.Popen object.
 
   - Forces English output since it's easier to parse the stdout if it is always
     in English.
   - Sets shell=True on windows by default. You can override this by forcing
     shell parameter to a value.
   - Adds support for VOID to not buffer when not needed.
 
-  Note: Popen() can throw OSError when cwd or args[0] doesn't exist.
+  Note: Popen() can throw OSError when cwd or args[0] doesn't exist. Translate
+  exceptions generated by cygwin when it fails trying to emulate fork().
   """
   # Make sure we hack subprocess if necessary.
   hack_subprocess()
   add_kill()
 
   env = get_english_env(kwargs.get('env'))
   if env:
     kwargs['env'] = env
   if kwargs.get('shell') is None:
     # *Sigh*:  Windows needs shell=True, or else it won't search %PATH% for the
@@ skipping 146 matching lines @@
   - Works even prior to python 2.7.
   - Blocks stdin by default since no output will be visible.
   """
   if kwargs.get('stdin') is None:
     kwargs['stdin'] = VOID
   if kwargs.get('stdout') is None:
     kwargs['stdout'] = PIPE
   if kwargs.get('stderr') is None:
     kwargs['stderr'] = STDOUT
   return check_call_out(args, **kwargs)[0]