[plt-scheme] all-except in require

Hi Matthew, Robby,

Thanks for the early-morning help. This one is just a question, really:

In the (require ...) form, I can do an 'all-except'. No error is 
generated when I 'except' a name that doesn't exist:

(module foo mzscheme
   (provide (all-defined))
   (define x 3)
   (define y 5))

(module bar mzscheme
   (require (all-except foo z))
   (printf "Sum: ~a" (+ x y)))

Does it make sense to be able to "except" a name that isn't defined? It 
doesn't seem to hurt anything to allow it, but I noted it, and thought 
I'd ask.

While I'm at it, 'all-except' in the 'require' and 'all-from-except' in 
the 'provide' are very close in name, and semantically the same. Was it 
an intentional choice to name them differently, or just how things evolved?

Thanks again,
Matt