Reapply r79779: "Removed gclient_utils.Popen() and use subprocess2's version instead."

subprocess2.py

Index: subprocess2.py
diff --git a/subprocess2.py b/subprocess2.py
index c9057ac6ae19dd32c996b6c333bd5cc071a21d84..d4fa5781d6ee1be9f99b14ab17c156f2b02f1260 100644
--- a/subprocess2.py
+++ b/subprocess2.py
@@ -8,6 +8,7 @@ In theory you shouldn't need anything else in subprocess, or this module failed.
 """
 
 from __future__ import with_statement
+import errno
 import logging
 import os
 import subprocess
@@ -124,7 +125,7 @@ def get_english_env(env):
 
 
 def Popen(args, **kwargs):
-  """Wraps subprocess.Popen().
+  """Wraps subprocess.Popen() with various workarounds.
 
   Returns a subprocess.Popen object.
 
@@ -134,7 +135,8 @@ def Popen(args, **kwargs):
     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()
@@ -160,7 +162,20 @@ def Popen(args, **kwargs):
     kwargs['stdout'] = open(os.devnull, 'w')
   if kwargs.get('stderr') in (VOID, os.devnull):
     kwargs['stderr'] = open(os.devnull, 'w')
-  return subprocess.Popen(args, **kwargs)
+  try:
+    return subprocess.Popen(args, **kwargs)
+  except OSError, e:
+    if e.errno == errno.EAGAIN and sys.platform == 'cygwin':
+      # Convert fork() emulation failure into a CalledProcessError().
+      raise CalledProcessError(
+          e.errno,
+          args,
+          kwargs.get('cwd'),
+          'Visit '
+          'http://code.google.com/p/chromium/wiki/CygwinDllRemappingFailure to '
+          'learn how to fix this error; you need to rebase your cygwin dlls',
+          None)
+    raise
 
 
 def call(args, timeout=None, **kwargs):