Only include associations when the relevant rows have content

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1079 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/associations.rb

@@ -652,7 +652,7 @@ def construct_finder_sql_with_included_associations(reflections)
 
         def extract_association_for_record(record, rows, reflection)
           association = rows.collect do |row| 
-            if row["#{table_name}__#{primary_key}"] == record.id.to_s
+            if row["#{table_name}__#{primary_key}"] == record.id.to_s && !row["#{reflection.klass.table_name}__#{reflection.klass.primary_key}"].nil?
               reflection.klass.send(:instantiate, extract_record(reflection.klass.table_name, row))
             end
           end