[3.6] bpo-22635: subprocess.getstatusoutput doc update. (GH-3398) (#3411)

The `subprocess.getstatusoutput` API was inadvertently changed
in Python 3.3.4.  Document the change, it is too late to undo the
API change now as it has shipped in many stable releases.
(cherry picked from commit 738b7d97)

Doc/library/subprocess.rst

@@ -1166,27 +1166,32 @@ handling consistency are valid for these functions.
 
 .. function:: getstatusoutput(cmd)
 
-   Return ``(status, output)`` of executing *cmd* in a shell.
+   Return ``(exitcode, output)`` of executing *cmd* in a shell.
 
    Execute the string *cmd* in a shell with :meth:`Popen.check_output` and
-   return a 2-tuple ``(status, output)``. The locale encoding is used;
+   return a 2-tuple ``(exitcode, output)``. The locale encoding is used;
    see the notes on :ref:`frequently-used-arguments` for more details.
 
    A trailing newline is stripped from the output.
-   The exit status for the command can be interpreted
-   according to the rules for the C function :c:func:`wait`.  Example::
+   The exit code for the command can be interpreted as the return code
+   of subprocess.  Example::
 
       >>> subprocess.getstatusoutput('ls /bin/ls')
       (0, '/bin/ls')
       >>> subprocess.getstatusoutput('cat /bin/junk')
-      (256, 'cat: /bin/junk: No such file or directory')
+      (1, 'cat: /bin/junk: No such file or directory')
       >>> subprocess.getstatusoutput('/bin/junk')
-      (256, 'sh: /bin/junk: not found')
+      (127, 'sh: /bin/junk: not found')
+      >>> subprocess.getstatusoutput('/bin/kill $$')
+      (-15, '')
 
    Availability: POSIX & Windows
 
    .. versionchanged:: 3.3.4
-      Windows support added
+      Windows support was added.
+
+      The function now returns (exitcode, output) instead of (status, output)
+      as it did in Python 3.3.3 and earlier.  See :func:`WEXITSTATUS`.
 
 
 .. function:: getoutput(cmd)