warnings.catch_warnings() now returns a list or None instead of the custom
WarningsRecorder object. This makes the API simpler to use as no special object
must be learned.

Closes issue 3781.
Review by Benjamin Peterson.
diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py
index 4d570d0..d82d391 100644
--- a/Lib/test/test_random.py
+++ b/Lib/test/test_random.py
@@ -191,7 +191,7 @@
 
     def test_bigrand(self):
         # Verify warnings are raised when randrange is too large for random()
-        with test_support.catch_warning():
+        with warnings.catch_warnings():
             warnings.filterwarnings("error", "Underlying random")
             self.assertRaises(UserWarning, self.gen.randrange, 2**60)