Nullification and sunset of copyleft provision refer to conditions 4-7.
(Section 4, general conditions including attribution, is wiped too.
I think symmetrical licensing condition (8) is questionable, but that's
the scope of another issue. Also, nullification of copyleft should be
wiped at sunset, it's a logical consequence, but there's no harm in
keeping it either, it won't mean anything.)

Signed-off-by: enyst <engel.nyst@gmail.com>