has_many association proxy delete method sometimes deletes too liberally

I am not able to reproduce this case with rails3 edge.

class Car < ActiveRecord::Base
  has_many :brakes

  def self.lab
    Car.create(:name => 'John')
    car = Car.last
    brakes = car.brakes
    brake = brakes.create(:name => 'wow')
    puts "brake id is #{brake.id}"
    brakes.build(:name => 'cursed brake')
    brakes.each do |brake|
      puts "processing brake #{brake.name}"
      car.brakes.delete(brake) 
    end
  end
end

The output of Car.lab is

SQL (0.4ms) INSERT INTO "cars" ("name") VALUES ('John')
Car Load (0.3ms) SELECT "cars". FROM "cars" ORDER BY cars.id DESC LIMIT 1 SQL (0.4ms) INSERT INTO "brakes" ("car_id", "name") VALUES (8, 'wow') brake id is 13
SQL (0.5ms) INSERT INTO "brakes" ("car_id", "name") VALUES (8, 'airblad') Brake Load (0.3ms) SELECT "brakes". FROM "brakes" WHERE ("brakes".car_id = 8) processing brake wow
SQL (0.3ms) UPDATE "brakes" SET "car_id" = NULL WHERE ("brakes"."car_id" = 8 AND "brakes"."id" IN (13)) processing brake cursed brake
=> [#]

Everything looks okay to me.

Actually I wasn't proposing anything, what I was experiencing was a straight-up bug. However, I eventually tracked this down to a condition in my application, so there is in fact no bug here. Please make this ticket invalid.