On Wed, Jan 5, 2011 at 1:58 AM, Guido van Rossum <firstname.lastname@example.org
> On Tue, Jan 4, 2011 at 2:49 AM, Michael Foord <email@example.com
>> I think someone else pointed this out, but replacing builtins externally to
>> a module is actually common for testing. In particular replacing the open
>> function, but also other builtins, is often done temporarily to replace it
>> with a mock. It seems like this optimisation would break those tests.
> Hm, I already suggested to make an exception for open, (and one should
> be added for __import__) but if this is done for other builtins that
> is indeed a problem. Can you point to example code doing this?