[krbdev.mit.edu #5462] Vista no longer returns enctype 0 for unavailable session keys

[Sam Hartman via RT]

I'd like to explore options for a runtime test.  I understand that
you've thought about this, but perhaps once you get the hotfix, we
could walk through options for a runtime test that works in practice
even if Microsoft did not design one.

I don't want this to block anything.