Ruby 1.9

Enumerable#join acts oddly for nested Enumerables. Should the output not be the same for both Array and E?

    $ cat /tmp/join.rb
    class E
      include Enumerable
      def initialize(*args)
        @e = args
      end
      def each
        @e.each {|e| yield e}
      end
    end
    p [1,[2,[3,4]]].join(':')
    p E.new(1, E.new(2, E.new(3, 4))).join(':')

    $ ruby -vw /tmp/join.rb 
    ruby 1.9.2dev (2009-07-08 trunk 23987) [i686-linux]
    "1:2:3:4"
    "1:#<E:0x957f298>"