Do not override attributes on dup by default scopes

activerecord/CHANGELOG.md

@@ -1,5 +1,9 @@
 ## unreleased ##
 
+*   Fix overriding of attributes by default_scope on `ActiveRecord::Base#dup`.
+
+    *Hiroshige UMINO*
+
 *   Fix issue with overriding Active Record reader methods with a composed object
     and using that attribute as the scope of a `uniqueness_of` validation.
     Backport #7072.

activerecord/lib/active_record/base.rb

@@ -553,7 +553,6 @@ def initialize_dup(other)
         @new_record  = true
 
         ensure_proper_type
-        populate_with_current_scope_attributes
         super
       end
 

activerecord/test/cases/dup_test.rb

@@ -113,5 +113,14 @@ def test_dup_validity_is_independent
       assert topic.invalid?
       assert duped.valid?
     end
+
+    def test_dup_with_default_scope
+      prev_default_scopes = Topic.default_scopes
+      Topic.default_scopes = [Topic.where(:approved => true)]
+      topic = Topic.new(:approved => false)
+      assert !topic.dup.approved?, "should not be overriden by default scopes"
+    ensure
+      Topic.default_scopes = prev_default_scopes
+    end
   end
 end