Unexpected python exception

[Andreas Löscher]

Python searches for Variables not only in local or global scoop but also
in __builtins__. If you do something like __builtins__.os = os, than
this variable should be accessible global. 

If you then write something like:
def B():
	os.stat("/")
	import os

Python recognises on compile time, that os is a local variable in B and
allocates memory for it. All reading or writing now goes to the local
variable and not the one in __builtins__. And the local variable has
never been assigned to a value and an Exception is thrown.

Best