ObjectSpace#allocation_class_path not working as expected

[Rajeev Bharshetty]

Using Ruby Version 2.1.2

class A
  def foo
    ObjectSpace::trace_object_allocations do
      obj = Object.new
      p "#{ObjectSpace::allocation_class_path(obj)}"
    end
  end
end

A.new.foo #=> "Class"

The above method is expected to return back the allocation class path of the object.

But I am getting an empty string back instead of "Class".

Is it an implementation bug in the method or the documentation is not updated.

Thanks