YAML parser do not escape nested yaml string correctly

Looks like the yaml serilization has some problem when there is a nested yaml serialized string

require 'test/unit'
require 'active_support'
require 'yaml'

class TestRoundTripSerialization < Test::Unit::TestCase
def test_roundtrip_serialization_with_yaml
hash = HashWithIndifferentAccess.new
hash['kind'] = 'human'
need_to_be_serialized = {:first => 'something', :second_params => hash}
a = {:x => need_to_be_serialized.to_yaml}
assert_equal need_to_be_serialized, YAML.load(YAML.load(a.to_yaml)[:x])
end
end

This testcase failed both on macos and windows xp. But the behavior is kind of differen on two platform. Sometime I got extra '\' on the serialized yaml string on windows.