Module#public does not follow method redefinition

[headius]

From http://jira.codehaus.org/browse/JRUBY-3917 filed by @shugo.

Module#public does not follow method redefinition.

  class Foo
    private
    def foo
      p :foo
    end
  end

  class Bar < Foo
    public :foo
  end

  class Foo
    def foo
      p :redefined
    end
  end

  b = Bar.new
  b.foo # :foo, but it should be :redefined

FYI, in CRuby, NODE_ZSUPER is used to implement it. Futhermore, Kernel#method and Module#instance_method return the method of the superclass to hide NODE_ZSUPER.