Addresses Issue #10838: The subprocess now module includes
SubprocessError and TimeoutError in its list of exported names for the
users wild enough to use "from subprocess import *".

MAXFD, mswindows and list2cmdline should be dealt with (renamed or
moved) in separate commits.

Committed at 35,000ft.  Thanks chromebook free gogo wifi passes!
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 6d2c4f5..1c7eb9e 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -433,7 +433,10 @@
 
 
 __all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput",
-           "getoutput", "check_output", "CalledProcessError", "DEVNULL"]
+           "getoutput", "check_output", "CalledProcessError", "DEVNULL",
+           "SubprocessError", "TimeoutExpired"]
+           # NOTE: We intentionally exclude list2cmdline as it is
+           # considered an internal implementation detail.  issue10838.
 
 if mswindows:
     from _winapi import (CREATE_NEW_CONSOLE, CREATE_NEW_PROCESS_GROUP,