Fix crash when loading fixture with belongs_to association defined in abstract base class.

activerecord/lib/active_record/fixtures.rb

@@ -669,7 +669,7 @@ def table_rows
                   row[association.foreign_type] = $1
                 end
 
-                fk_type = association.active_record.type_for_attribute(fk_name).type
+                fk_type = reflection_class.type_for_attribute(fk_name).type
                 row[fk_name] = ActiveRecord::FixtureSet.identify(value, fk_type)
               end
             when :has_many

activerecord/test/cases/fixtures_test.rb

@@ -16,6 +16,7 @@
 require 'models/matey'
 require 'models/parrot'
 require 'models/pirate'
+require 'models/doubloon'
 require 'models/post'
 require 'models/randomly_named_c1'
 require 'models/reply'
@@ -903,3 +904,12 @@ class FixturesWithDefaultScopeTest < ActiveRecord::TestCase
     assert_equal "special", bulbs(:special).name
   end
 end
+
+class FixturesWithAbstractBelongsTo < ActiveRecord::TestCase
+  fixtures :pirates, :doubloons
+
+  test "creates fixtures with belongs_to associations defined in abstract base classes" do
+    assert_not_nil doubloons(:blackbeards_doubloon)
+    assert_equal pirates(:blackbeard), doubloons(:blackbeards_doubloon).pirate
+  end
+end

activerecord/test/fixtures/doubloons.yml

+blackbeards_doubloon:
+  pirate: blackbeard
+  weight: 2

activerecord/test/models/doubloon.rb

+class AbstractDoubloon < ActiveRecord::Base
+  # This has functionality that might be shared by multiple classes.
+
+  self.abstract_class = true
+  belongs_to :pirate
+end
+
+class Doubloon < AbstractDoubloon
+  # This uses an abstract class that defines attributes and associations.
+
+  self.table_name = 'doubloons'
+end

activerecord/test/schema/schema.rb

@@ -266,6 +266,11 @@ def except(adapter_names_to_exclude)
     t.string  :alias
   end
 
+  create_table :doubloons, force: true do |t|
+    t.integer :pirate_id
+    t.integer :weight
+  end
+
   create_table :edges, force: true, id: false do |t|
     t.column :source_id, :integer, null: false
     t.column :sink_id,   :integer, null: false