Builtin singleton & instance_methods

Hi,

given:

s="some string"

def s.some_meth
end

class << s
     p self.instance_methods(false)
end

why instance_methods doesn't return only the name of a method defined for singletons class ? I've found that this is also true for other builtin types that have _basic_ structure. I've also looked into ins_methods_push and class_instance_method_list in Ruby sources, but haven't found any clues...

JRuby behaves the expected way...

lopex