Make all classes new-style in Python 2, allowing them to be used with ExitStack.

contextlib2.py

@@ -179,7 +179,7 @@ class closing(object):
         self.thing.close()
 
 
-class _RedirectStream:
+class _RedirectStream(object):
 
     _stream = None
 
@@ -219,7 +219,7 @@ class redirect_stderr(_RedirectStream):
     _stream = "stderr"
 
 
-class suppress:
+class suppress(object):
     """Context manager to suppress specified exceptions
 
     After the exception is suppressed, execution proceeds with the next

test_contextlib2.py

@@ -763,6 +763,11 @@ class TestRedirectStream:
         s = f.getvalue()
         self.assertEqual(s, "Hello World!\n")
 
+    def test_cm_is_exitstack_compatible(self):
+        with ExitStack() as stack:
+            # This shouldn't raise an exception.
+            stack.enter_context(self.redirect_stream(io.StringIO()))
+
 
 class TestRedirectStdout(TestRedirectStream, unittest.TestCase):
 
@@ -830,6 +835,11 @@ class TestSuppress(unittest.TestCase):
             1/0
         self.assertTrue(outer_continued)
 
+    def test_cm_is_exitstack_compatible(self):
+        with ExitStack() as stack:
+            # This shouldn't raise an exception.
+            stack.enter_context(suppress())
+
 if __name__ == "__main__":
     import unittest
     unittest.main()