fails:Object#dup preserves tainted state from the original
fails:Object#dup preserves untrusted state from the original
fails:Object#dup raises a TypeError for NilClass
fails:Object#dup raises a TypeError for TrueClass
fails:Object#dup raises a TypeError for FalseClass
fails:Object#dup raises a TypeError for Fixnum
fails:Object#dup raises a TypeError for Symbol
