anchor.diff:          .toList();
     }
   
  -  void trackInstance(ManagedObject instance) {
  -    var typeMap = trackedObjects[instance.entity.tableName];
  -    if (typeMap == null) {
  -      typeMap = {};
  -      trackedObjects[instance.entity.tableName] = typeMap;
  -    }
  -
  -    typeMap[instance[instance.entity.primaryKey]] = instance;
  -  }
  -
     ManagedObject getExistingInstance(
         ManagedEntity entity, dynamic primaryKeyValue) {
  -    var byType = trackedObjects[entity.tableName];
  +    var byType = distinctObjects[entity.tableName];
       if (byType == null) {
         return null;
       }
  
positive.code: class ManagedInstantiator {
    ManagedInstantiator(this.rootEntity);
  
    Map<String, Map<dynamic, ManagedObject>> trackedObjects = {};
    List<PropertyToColumnMapper> orderedMappingElements;
    ManagedEntity rootEntity;
  
  
negative.code:     var instance = entity.newInstance();
  
      instance[entity.primaryKey] = primaryKeyValue;
  
      var typeMap = distinctObjects[instance.entity.tableName];
      if (typeMap == null) {
        typeMap = {};
        distinctObjects[instance.entity.tableName] = typeMap;
      }
  
      typeMap[instance[instance.entity.primaryKey]] = instance;
  
      return instance;
    }
  