It's still there, but masked by the creation of a new 'None':
>>> None = 1
>>> import builtin
As Guido stated, in a module or procedure, this will create a
new local None.
I uncovered my problem when I edited a module that assigned to
None, and inserted an assignment to another variable OF None
before that assignment. The compiler then complained with a
NameError: the use of None on the LHS told it to create a new
local variable, but the use on the RHS before it had a value
was an error. ( without the assignment, it would have used the
Global value of None. )
I only continue to beat this dead horse into the ground because
it displays some of the peculiarities of scope.