asyncio.tasks: Fix CoroWrapper to workaround yield-from bug in CPython < 3.4.1

Closes issue #21209.
diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
index 153f731..0366da3 100644
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -49,7 +49,10 @@
     def __next__(self):
         return next(self.gen)
 
-    def send(self, value):
+    def send(self, *value):
+        # We use `*value` because of a bug in CPythons prior
+        # to 3.4.1. See issue #21209 and test_yield_from_corowrapper
+        # for details.  This workaround should be removed in 3.5.0.
         return self.gen.send(value)
 
     def throw(self, exc):