Logged In: YES 
user_id=34209

Possibly related is the discovery of free variables (used
when forming closures) and optimized-out codeblocks:

>>> def foo(x):
...     def bar():
...         if 0:
...             print x
...     return bar

In 2.4, there is no closure:
>>> foo.func_code.co_cellvars
()
>>> foo(5).func_closure
>>>

In 2.5, there is:
>>> foo.func_code.co_cellvars
('x',)
>>> foo(5).func_closure
(<cell at 0x2b9abf6d7e30: int object at 0x6b6580>,)

(I don't think it's unreasonable to declare the old
behaviour bugged, though :-)