#6276: Remove usage of nested() in favor of new with statement with multiple managers.

Lib/test/test_signal.py

 import unittest
 from test import test_support
-from contextlib import closing, nested
+from contextlib import closing
 import gc
 import pickle
 import select
@@ -146,8 +146,8 @@ class InterProcessSignalTests(unittest.TestCase):
         # re-raises information about any exceptions the child
         # throws. The real work happens in self.run_test().
         os_done_r, os_done_w = os.pipe()
-        with nested(closing(os.fdopen(os_done_r)),
-                    closing(os.fdopen(os_done_w, 'w'))) as (done_r, done_w):
+        with closing(os.fdopen(os_done_r)) as done_r, \
+             closing(os.fdopen(os_done_w, 'w')) as done_w:
             child = os.fork()
             if child == 0:
                 # In the child process; run the test and report results