Rails Ruby on Rails

It seems that combinaison of accepts_nested_attributes_for and attributes= is broken into rails 2.3.8.
The problem occurs whith following models :

class Book < ActiveRecord::Base
  has_many :authors
  accepts_nested_attributes_for authors
end

class Author < ActiveRecord::Base
  belongs_to :book
end

and a params hash like this :

params = {:name=>"a great book", "authors_attributes"=>{"1"=>{:id"=>"2", "_destroy"=>"", :name => "Boney M"}}}

Calling

book.attributes=params

do not set @loaded to true into authors AssociationProxy of object book. So the next call to

book.authors

will reload author objects from database.

This was not the case in rails 2.3.5, What is the normal behaviour ?

ps : I saw ticket 2646 and it seems to me to be a different problem.