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/decimal.py

@@ -2196,8 +2196,6 @@ class ContextManager(object):
         return self.new_context
     def __exit__(self, t, v, tb):
         setcontext(self.saved_context)
-        if t is not None:
-            raise t, v, tb
 
 class Context(object):
     """Contains the context for a Decimal instance.