diff -r 0fd72636de2b Lib/subprocess.py
--- a/Lib/subprocess.py	Fri Sep 20 23:28:27 2013 +0300
+++ b/Lib/subprocess.py	Mon Sep 23 15:47:29 2013 +0300
@@ -731,6 +731,9 @@
 
 
 class Popen(object):
+
+    _child_created = False  # Set here since __del__ checks it
+
     def __init__(self, args, bufsize=-1, executable=None,
                  stdin=None, stdout=None, stderr=None,
                  preexec_fn=None, close_fds=_PLATFORM_DEFAULT_CLOSE_FDS,
@@ -741,7 +744,6 @@
         """Create new Popen instance."""
         _cleanup()
 
-        self._child_created = False
         self._input = None
         self._communication_started = False
         if bufsize is None:
@@ -883,11 +885,8 @@
         # Wait for the process to terminate, to avoid zombies.
         self.wait()
 
-    def __del__(self, _maxsize=sys.maxsize, _active=_active):
-        # If __init__ hasn't had a chance to execute (e.g. if it
-        # was passed an undeclared keyword argument), we don't
-        # have a _child_created attribute at all.
-        if not getattr(self, '_child_created', False):
+    def __del__(self, _maxsize=sys.maxsize):
+        if not self._child_created:
             # We didn't get to successfully create a child process.
             return
         # In case the child hasn't been waited on, check if it's done.
@@ -1430,7 +1429,7 @@
 
         def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,
                 _WTERMSIG=os.WTERMSIG, _WIFEXITED=os.WIFEXITED,
-                _WEXITSTATUS=os.WEXITSTATUS):
+                _WEXITSTATUS=os.WEXITSTATUS, _SubprocessError=SubprocessError):
             # This method is called (indirectly) by __del__, so it cannot
             # refer to anything outside of its local scope."""
             if _WIFSIGNALED(sts):
@@ -1439,11 +1438,11 @@
                 self.returncode = _WEXITSTATUS(sts)
             else:
                 # Should never happen
-                raise SubprocessError("Unknown child exit status!")
+                raise _SubprocessError("Unknown child exit status!")
 
 
         def _internal_poll(self, _deadstate=None, _waitpid=os.waitpid,
-                _WNOHANG=os.WNOHANG, _ECHILD=errno.ECHILD):
+                _WNOHANG=os.WNOHANG, _ECHILD=errno.ECHILD, _OSError=OSError):
             """Check if child process has terminated.  Returns returncode
             attribute.
 
@@ -1456,7 +1455,7 @@
                     pid, sts = _waitpid(self.pid, _WNOHANG)
                     if pid == self.pid:
                         self._handle_exitstatus(sts)
-                except OSError as e:
+                except _OSError as e:
                     if _deadstate is not None:
                         self.returncode = _deadstate
                     elif e.errno == _ECHILD: