never retain a generator's caller's exception state on the generator after a yield/return
This requires some trickery to properly save the exception state if the
generator creates its own exception state.
diff --git a/Misc/NEWS b/Misc/NEWS
index d763e0f..250acc2 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@
Core and Builtins
-----------------
+- When a generator yields, do not retain the caller's exception state on the
+ generator.
+
- Issue #12475: Prevent generators from leaking their exception state into the
caller's frame as they return for the last time.