asyncio: Fix with github

See https://github.com/python/asyncio/pull/295 for details
diff --git a/Lib/asyncio/test_utils.py b/Lib/asyncio/test_utils.py
index e06ac06..8170533 100644
--- a/Lib/asyncio/test_utils.py
+++ b/Lib/asyncio/test_utils.py
@@ -24,6 +24,7 @@
     ssl = None
 
 from . import base_events
+from . import compat
 from . import events
 from . import futures
 from . import selectors
@@ -421,6 +422,16 @@
         # in an except block of a generator
         self.assertEqual(sys.exc_info(), (None, None, None))
 
+    if not compat.PY34:
+        # Python 3.3 compatibility
+        def subTest(self, *args, **kwargs):
+            class EmptyCM:
+                def __enter__(self):
+                    pass
+                def __exit__(self, *exc):
+                    pass
+            return EmptyCM()
+
 
 @contextlib.contextmanager
 def disable_logger():