bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() (GH-7467)

diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index 1a58b50..c06ec73 100644
--- a/Lib/contextlib.py
+++ b/Lib/contextlib.py
@@ -187,7 +187,7 @@
             # in this implementation
             try:
                 await self.gen.athrow(typ, value, traceback)
-                raise RuntimeError("generator didn't stop after throw()")
+                raise RuntimeError("generator didn't stop after athrow()")
             except StopAsyncIteration as exc:
                 return exc is not value
             except RuntimeError as exc: