Changes for clojure.core/butlast

boxie on Sat, 06 Nov 2010
user=> (butlast [1 2 3])
(1 2)
user=> (butlast (butlast [1 2 3]))
(1)
user=> (butlast (butlast (butlast [1 2 3])))
nil
dpritchett on Tue, 13 Jul 2010
user=> (butlast '(1 2 3 4 5))
(1 2 3 4)