Partially revert [5660] - makes more trouble than it resolves. References #5704, closes #6766.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5753 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

@@ -12,8 +12,6 @@
 
 * Added counter optimization for AssociationCollection#any? so person.friends.any? won't actually load the full association if we have the count in a cheaper form [DHH]
 
-* Subclasses of an abstract class work with single-table inheritance.  #5704 [nick+rails@ag.arizona.edu, Ryan Davis, Jeremy Kemper]
-
 * Change fixture_path to a class inheritable accessor allowing test cases to have their own custom set of fixtures. #6672 [zdennis]
 
 * Quote ActiveSupport::Multibyte::Chars.  #6653 [Julian Tarkhanov]

activerecord/lib/active_record/base.rb

@@ -816,7 +816,7 @@ module ActiveRecord #:nodoc:
       end
 
       def descends_from_active_record? # :nodoc:
-        superclass.abstract_class? || !columns_hash.include?(inheritance_column)
+        superclass == Base || !columns_hash.include?(inheritance_column)
       end
 
 
@@ -1360,7 +1360,7 @@ module ActiveRecord #:nodoc:
 
         # Returns the class descending directly from ActiveRecord in the inheritance hierarchy.
         def class_of_active_record_descendant(klass)
-          if klass.superclass.abstract_class?
+          if klass.superclass == Base || klass.superclass.abstract_class?
             klass
           elsif klass.superclass.nil?
             raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord"
@@ -1481,9 +1481,6 @@ module ActiveRecord #:nodoc:
         end
     end
 
-    # ActiveRecord::Base is abstract.
-    self.abstract_class = true
-
     public
       # New objects can be instantiated as either empty (pass no construction parameter) or pre-set with
       # attributes but not yet saved (pass a hash with key names matching the associated table column names).

activerecord/test/base_test.rb

@@ -1365,7 +1365,7 @@ class BasicsTest < Test::Unit::TestCase
   end
 
   def test_abstract_class
-    assert ActiveRecord::Base.abstract_class?
+    assert !ActiveRecord::Base.abstract_class?
     assert LoosePerson.abstract_class?
     assert !LooseDescendant.abstract_class?
   end
@@ -1408,7 +1408,7 @@ class BasicsTest < Test::Unit::TestCase
     assert !StiPost.descends_from_active_record?
 
     # Concrete subclasses an abstract class which has a type column.
-    assert SubStiPost.descends_from_active_record?
+    assert !SubStiPost.descends_from_active_record?
   end
 
   def test_find_on_abstract_base_class_doesnt_use_type_condition