Index: Lib/subprocess.py
===================================================================
--- Lib/subprocess.py	(revision 78823)
+++ Lib/subprocess.py	(working copy)
@@ -389,7 +389,6 @@
 """
 
 import sys
-mswindows = (sys.platform == "win32")
 
 import os
 import types
@@ -412,6 +411,15 @@
         return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
 
 
+try:
+    import _subprocess
+except ImportError:
+    mswindows = False
+else:
+    mswindows = True
+    del _subprocess
+
+
 if mswindows:
     import threading
     import msvcrt