多对多关联，在belongsToMany()后，接链式操作的bug

Reproduce the reported many-to-many eager-loading case using the User, Book, and UserBook models, comparing belongsToMany() with and without chained order() and with() closures. Inspect the eager-loading path and generated SQL around these entry points; done means every user retains the correct books while ordering and append-style constraints still work.

user表 ( id, name )
数据
(1, 张三),
(2, 李四),
(3, 王五)

book表[ id, name ]
数据
(1, 《PHP》),
(2, 《Java》),
(3, 《Python》),
(4, 《Go》),

中间表 user_book [ id, user_id, book_id]
数据
(1, 1, 1),
(2, 2, 2),
(3, 2, 3),
(4, 3, 1),
(5, 3, 2),
(6, 3, 4)

                                +--------+
                      +-------> |1  PHP  | <------+
  +--------+          |         +--------+        |
1 |zhangsan| +--------+                           |
  +--------+                    +--------+        |
                      +-------> |2  Java | <---+  |
  +--------+          |         +--------+     |  |
2 |  lisi  | +--------+                        |  |
  +--------+          |         +--------+     |  |
                      +-------> |3 Python|     |  |
  +--------+                    +--------+     |  |
3 | wangwu | +------+                          |  |
  +--+--+--+        |           +--------+     |  |
     |  |           +---------> |4   Go  |     |  |
     |  |                       +--------+     |  |
     |  |                                      |  |
     |  +--------------------------------------+  |
     |                                            |
     +--------------------------------------------+

类

class User extends Model {
    protected $table = 'user';

    public function books(){
        return $this->belongsToMany(Book::class, UserBook::class)->order(['Book.id'=>'DESC']);
    }
}

class Book extends Model {
    protected $table = 'book';
}

class UserBook extends Pivot{
    protected $table = 'user_book';
}

查询代码

$users = User::where('id', '>', 0)->with(['books'])->select();

在think-orm v2.0.31中的结果【正确】

[
    {
        "id": 1,
        "name": "张三",
        "books": [
            {
                "id": 1,
                "name": "《PHP》"
            }
        ]
    },
    {
        "id": 2,
        "name": "李四",
        "books": [
            {
                "id": 3,
                "name": "《Python》"
            },
            {
                "id": 2,
                "name": "《Java》"
            }
        ]
    },
    {
        "id": 3,
        "name": "王五",
        "books": [
            {
                "id": 4,
                "name": "《Go》"
            },
            {
                "id": 2,
                "name": "《Java》"
            },
            {
                "id": 1,
                "name": "《PHP》"
            }
        ]
    }
]

而在think-orm v2.0.34中的结果【错误】

[
    {
        "id": 1,
        "name": "张三",
        "books": []    // 【丢失了books数据】
    },
    {
        "id": 2,
        "name": "李四",
        "books": []    // 【丢失了books数据】
    },
    {
        "id": 3,
        "name": "王五",
        "books": [     // 【books数据正常】
            {
                "id": 4,
                "name": "《Go》"
            },
            {
                "id": 2,
                "name": "《Java》"
            },
            {
                "id": 1,
                "name": "《PHP》"
            }
        ]
    }
]

对比发现，v2.0.31的结果正常，所有的user的books正确；
而v2.0.34 中的结果里，只有最后一个user中有books，其他user的books都是 [ ]

日志中的SQL对比
v2.0.34

SELECT `book`.*,`pivot`.`id` AS `pivot__id`,`pivot`.`user_id` AS `pivot__user_id`,`pivot`.`book_id` AS `pivot__book_id`,`pivot` FROM `book` INNER JOIN `user_book` `pivot` ON `pivot`.`book_id`=`book`.`id` 
WHERE  `pivot`.`user_id` IN (1,2,3)

v2.0.34

SELECT `book`.*,`pivot`.`id` AS `pivot__id`,`pivot`.`user_id` AS `pivot__user_id`,`pivot`.`book_id` AS `pivot__book_id` FROM `book` INNER JOIN `user_book` `pivot` ON `pivot`.`book_id`=`book`.`id` 
WHERE  `pivot`.`user_id` = 3 ORDER BY `Book`.`id` DESC

区别：前者 user_id IN (1, 2, 3)，而后者 user_id = 3

不仅在模型中定义关联时，belongsToMany，后接其他函数有这个问题
return $this->belongsToMany(...)->order();

在查询时，with()中指定闭包也会出现此bug，如：

$users = User::where('id', '>', 0)->with(['books'=>function($query){
    $query->append(['pinyin']);    // append 拼音字段
}])->select();