@eLobato, ::symbolize_attrs! is what caused test to fail is functional/hosts_controller_test "BMC password updates successful even if attrs serialized field is the only dirty field".  I really have no idea why.  I also don't understand though why are you calling :symbolize_attrs!?

I moved the callback :symbolize_attrs! from before_validation to before_save and the tests passed.  I wish I knew why :)