DM: lazy-loaded properties materialized in hooks (:save) reset parental reference updates for children

1_script.rb

#!/usr/bin/ruby

require 'rubygems'
require 'data_objects'  # current master @ ed1ceefc
require 'dm-core'       # current master @ 73860575
require 'dm-migrations' # current master @ ab608e81

class Order
    include ::DataMapper::Resource

    property :id, Serial

    has 0..n, :order_items
end

class OrderItem
    include ::DataMapper::Resource

    property :id,     Serial
    property :queues, String, :default => '', :lazy => true

    belongs_to :order

    before :save do
        if $LAZY_LOAD
            warn "materializing lazy_loaded property"
            self.queues
        end
    end
end

::DataMapper.setup(:default, 'mysql://127.0.0.1/test')

$LAZY_LOAD = false

2.times do |i|
    ::DataMapper.auto_migrate!

    warn "\n--- pass #{i} (lazy load property in save hook == #{$LAZY_LOAD})\n"

    order      = Order.create
    order_item = OrderItem.create(:queues => 'balls', :order => order)
    new_order  = Order.create

    order.order_items.all.each do |item|

        warn "item #{item.id} has order #{item.order.id}, updating with new_order #{new_order.id}"
        item.update(:order => new_order)

        if item.order.id == new_order.id
            warn "EXPECTED: item #{item.id} now has order #{item.order.id}"
        else
            # NOTE: item.dirty? == false, and it's still the wrong value after item.reload.
            warn "NOT EXPECTED: item #{item.id} now has order #{item.order.id} (wanted order #{new_order.id})"
        end
    end

    # Second time through, materialize the lazy-loaded property.
    $LAZY_LOAD = true
end

2_output.txt

$ ruby child_update_fail.rb 

--- pass 0 (lazy load property in save hook == false)

item 1 has order 1, updating with new_order 2
EXPECTED: item 1 now has order 2

--- pass 1 (lazy load property in save hook == true)

materializing lazy_loaded property
item 1 has order 1, updating with new_order 2
materializing lazy_loaded property
NOT EXPECTED: item 1 now has order 1 (wanted order 2)
$