Changes for clojure.core/reversible?

jafingerhut on Wed, 28 Mar 2012
user=> (reversible? [])
true
user=> (reversible? '())
false
user=> (reversible? #{})
false
replore on Tue, 15 Nov 2011
user=> (reversible? [])
true
user=> (reversible? '())
false
user=> (reversible? #{})
false