subprocess.Popen.__exit__ doesn't wait for process end

Doc/library/subprocess.rst

--- a/Doc/library/subprocess.rst	Wed May 11 22:37:50 2011 +0800
+++ b/Doc/library/subprocess.rst	Wed May 11 18:35:39 2011 +0200
@@ -219,13 +219,19 @@
    *creationflags*, if given, can be :data:`CREATE_NEW_CONSOLE` or
    :data:`CREATE_NEW_PROCESS_GROUP`. (Windows only)
 
-   Popen objects are supported as context managers via the :keyword:`with` statement,
-   closing any open file descriptors on exit.
+   Popen objects are supported as context managers via the :keyword:`with` statement:
+   on exit, standard file descriptors are closed, and the process is waited for.
    ::
 
       with Popen(["ifconfig"], stdout=PIPE) as proc:
           log.write(proc.stdout.read())
 
+   .. note::
+
+      In the initial implementation, the process was not automatically waited
+      for upon exit from the context manager. Code intending to be compatible
+      with Python 2.7.1 and earlier should explicitly call :meth:`Popen.wait`.
+
    .. versionchanged:: 3.2
       Added context manager support.