Fix table_name in ActiveRecord with more than one abstract ancestors

When subclassing abstract_class table_name should be always computed
based on class name, no matter if superclass is subclassing base
or another abstract_class. So:

class FirstAbstract < ActiveRecord::Base
  self.abstract_class = true
end
class SecondAbstract < FirstAbstract
  self.abstract_class = true
end

class Post < SecondAbstract
  self.table_name #=> 'posts' (not 'second_abstracts')
end

1 files changed, 11 insertions, 0 deletions

diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 80a660717e..f5c139e85f 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -28,6 +28,13 @@ require 'rexml/document'
 require 'active_support/core_ext/exception'
 require 'bcrypt'
 
+class FirstAbstractClass < ActiveRecord::Base
+  self.abstract_class = true
+end
+class SecondAbstractClass < FirstAbstractClass
+  self.abstract_class = true
+end
+class Photo < SecondAbstractClass; end
 class Category < ActiveRecord::Base; end
 class Categorization < ActiveRecord::Base; end
 class Smarts < ActiveRecord::Base; end
@@ -1904,4 +1911,8 @@ class BasicsTest < ActiveRecord::TestCase
     assert_equal Teapot,              OtherTeapot.active_record_super
     assert_equal ActiveRecord::Model, CoolTeapot.active_record_super
   end
+
+  def test_table_name_with_2_abstract_subclasses
+    assert_equal "photos", Photo.table_name
+  end
 end