Namespace pollution due to YAML in 1.8.3/1.8.4

I just moved to 1.8.4 and noticed it broke my main Ruby application,
Nukumi2.  Nukumi2 uses a DSL based on method_missing to define fields.
It broke because YAML defines the method "taguri" in all classes to
be dumped.

> ruby-1.8.4/lib/yaml/tag.rb

class Module # :nodoc: all
    # Adds a taguri _tag_ to a class, used when dumping or loading the class
    # in YAML.  See YAML::tag_class for detailed information on typing and
    # taguris.
    def yaml_as( tag, sc = true )
        verbose, $VERBOSE = $VERBOSE, nil
        class_eval <<-"end;", __FILE__, __LINE__+1
            attr_writer :taguri
            def taguri
              ...
            end
            def self.yaml_tag_subclasses?; #{ sc ? 'true' : 'false' }; end
        end;
        YAML::tag_class tag, self
    ensure
        $VERBOSE = verbose
    end
end

This most nasty method should at least be called yaml_taguri, giving
YAML the yaml_ prefix for all global methods and instance variables,
especially because it can break software that is not directly related
to YAML (In Nukumi2, it's only used for a plugin.).
-- 
Christian Neukirchen  <[e-mail]>  http://chneukirchen.org