Interactions between 'new' and 'initialize' ?

In JRuby, I am extending an existing Java Class with a Ruby initialising
block by redefining the 'new' class method.
This works fine except for new classes which inherit from the original
class and have a different number of arguments.
These classes generate a 'wrong number of arguments' error.

The behavior seems not specific for Java Classes and is actually the
same for Ruby and JRuby.
The following example illustrates it, the first version works as
expected

class Parent
  def initialize(y)
      puts "I am parent #{y}"
  end
end

class Child < Parent
  def initialize(c1,c2)
    puts "I am a child #{c1} #{c2}"
  end
 end

 Parent.new('A')      # => I am parent A
 Child.new('B','C')   # => I am a child B C

 The next example adds a redefinition of Parent.new; Parent goes on to
work as expected, but Child fails:

class Parent
  class << self
    def new(arg)
      puts "redefining new for parent"
      super(arg)
    end
  end
  def initialize(y)
      puts "I am parent #{y}"
  end
end

class Child < Parent
  def initialize(c1,c2)
    puts "I am a child #{c1} #{c2}"
  end
end

Parent.new('A')      # => redefining new for Parent
                     # => I am parent A
Child.new('B','C')   # => ArgumentError: wrong number of arguments (2
for 1)

Is this behavior intentional or a bug? At least it is consistent  (Ruby
1.8.7, 1.9.1 JRuby 1.6.7)

I have tried using alias instead of super and changing the order of
redefining new and defining initialize. I also tried using class_eval
and taking the Person.new definition out of the original class
definition. All to no avail.
Any help would be appreciated.

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