EfRepository.cs - Why are some lines commented out in the source code?

        public void Update(T entity)
        {
            if (entity == null)
                throw new ArgumentNullException("entity");

            //if (!this._context.IsAttached(entity))
            //    this._entities.Attach(entity);

            this._context.SaveChanges();
        }

        public void Delete(T entity)
        {
            if (entity == null)
                throw new ArgumentNullException("entity");

            //if (!this._context.IsAttached(entity))
            //    this._entities.Attach(entity);

            this._entities.Remove(entity);

            this._context.SaveChanges();
        }