Factor out checks for duplicable objects. Closes #9333.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7908 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/base.rb

@@ -2205,13 +2205,7 @@ module ActiveRecord #:nodoc:
 
       def clone_attribute_value(reader_method, attribute_name)
         value = send(reader_method, attribute_name)
-
-        case value
-        when nil, Fixnum, true, false
-          value
-        else
-          value.clone
-        end
+        value.duplicable? ? value.clone : value
       rescue TypeError, NoMethodError
         value
       end

activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb

@@ -74,13 +74,10 @@ module ActiveRecord
               @query_cache[sql] = yield
             end
 
-          case result
-          when Array
+          if Array === result
             result.collect { |row| row.dup }
-          when nil, Fixnum, Float, true, false
-            result
           else
-            result.dup
+            result.duplicable? ? result.dup : result
           end
         rescue TypeError
           result