Bug #1704790: bind name "sys" locally in __del__ method so that it is

not cleared before __del__ is run.

Lib/subprocess.py

@@ -628,7 +628,7 @@ class Popen(object):
         return data
 
 
-    def __del__(self):
+    def __del__(self, sys=sys):
         if not self._child_created:
             # We didn't get to successfully create a child process.
             return