Except keys of `build_record`'s argument from `create_scope` in initialize_attributes

If argument of `build_record` has key and value which is same as
default value of database, we should also except the key from
`create_scope` in `initialize_attributes`.
Because at first `build_record` initialize record object with argument
of `build_record`, then assign attributes derived from Association's scope.
In this case `record.changed` does not include the key, which value is
same as default value of database, so we should add the key to except list.

Fix #21893.

2 files changed, 2 insertions, 0 deletions

diff --git a/activerecord/test/models/bulb.rb b/activerecord/test/models/bulb.rb
index a6e83fe353..c1e491e5c5 100644
--- a/activerecord/test/models/bulb.rb
+++ b/activerecord/test/models/bulb.rb
@@ -1,6 +1,7 @@
 class Bulb < ActiveRecord::Base
   default_scope { where(:name => 'defaulty') }
   belongs_to :car, :touch => true
+  scope :awesome, -> { where(frickinawesome: true) }
 
   attr_reader :scope_after_initialize, :attributes_after_initialize
 
diff --git a/activerecord/test/models/car.rb b/activerecord/test/models/car.rb
index 81263b79d1..778c22b1f6 100644
--- a/activerecord/test/models/car.rb
+++ b/activerecord/test/models/car.rb
@@ -4,6 +4,7 @@ class Car < ActiveRecord::Base
   has_many :funky_bulbs, class_name: 'FunkyBulb', dependent: :destroy
   has_many :failed_bulbs, class_name: 'FailedBulb', dependent: :destroy
   has_many :foo_bulbs, -> { where(:name => 'foo') }, :class_name => "Bulb"
+  has_many :awesome_bulbs, -> { awesome }, class_name: "Bulb"
 
   has_one :bulb