ActiveRecord::Associations::ClassMethods build is kind of misleading with unsaved parent objects

Hi there:

association.build returns unexpected behavior when returning a reference to a unsaved parent object

class Recipe < ActiveRecord::Base
  has_many :ingredients
end
class Ingredient < ActiveRecord::Base
  belongs_to :recipe
end

>> r = Recipe.new
=> #<Recipe id: nil, title: nil, created_at: nil, updated_at: nil>
>> r.ingredients.build
=> #<Ingredient id: nil, name: nil, recipe_id: nil, created_at: nil, updated_at: nil>
>> r.ingredients.first.recipe
=> nil

Why nil?

>> r.save
=> true
>> r.ingredients.first.recipe
=> #<Recipe id: 3, title: nil, created_at: "2011-03-30 02:49:58", updated_at: "2011-03-30 02:49:58">

One would assume a reference to the parent object would be returned and not nil even though the parent object has not been saved

( It would totally make sense if recipe_id would return nil, but recipe should be the unsaved parent object )

This picture sums up how I'm feeling right now: