[IronPython] Adding None to a set

[William Reade]

Hi guys

As if you didn't have enough on your plates already...

IronPython beta8:
 >>> st = set([])
 >>> st.add(None)
 >>> st
set([<type 'NoneType'>])

CPython:
 >>> st = set([])
 >>> st.add(None)
 >>> st
set([None])

Cheers
William