Um, I thought I'd already checked this in.

Anyway, this is the changes to the with-statement
so that __exit__ must return a true value in order
for a pending exception to be ignored.
The PEP (343) is already updated.

Lib/compiler/pyassem.py

@@ -779,7 +779,7 @@ class StackDepthTracker:
         'SETUP_EXCEPT': 3,
         'SETUP_FINALLY': 3,
         'FOR_ITER': 1,
-        'WITH_CLEANUP': 3,
+        'WITH_CLEANUP': -1,
         }
     # use pattern match
     patterns = [