在 Django 中链接多个 filter()，这是一个错误吗

我一直认为在Django中链接多个filter()调用与在单个调用中收集它们是一样的.

# Equivalent
Model.objects.filter(foo=1).filter(bar=2)
Model.objects.filter(foo=1,bar=2)

但是我在代码中遇到了一个复杂的查询集，而事实并非如此

class Inventory(models.Model):
    book = models.ForeignKey(Book)

class Profile(models.Model):
    user = models.OneToOneField(auth.models.User)
    vacation = models.BooleanField()
    country = models.CharField(max_length=30)

# Not Equivalent!
Book.objects.filter(inventory__user__profile__vacation=False).filter(inventory__user__profile__country='BR')
Book.objects.filter(inventory__user__profile__vacation=False, inventory__user__profile__country='BR')

生成的SQL为

SELECT "library_book"."id", "library_book"."asin", "library_book"."added", "library_book"."updated" FROM "library_book" INNER JOIN "library_inventory" ON ("library_book"."id" = "library_inventory"."book_id") INNER JOIN "auth_user" ON ("library_inventory"."user_id" = "auth_user"."id") INNER JOIN "library_profile" ON ("auth_user"."id" = "library_profile"."user_id") INNER JOIN "library_inventory" T5 ON ("library_book"."id" = T5."book_id") INNER JOIN "auth_user" T6 ON (T5."user_id" = T6."id") INNER JOIN "library_profile" T7 ON (T6."id" = T7."user_id") WHERE ("library_profile"."vacation" = False  AND T7."country" = BR )
SELECT "library_book"."id", "library_book"."asin", "library_book"."added", "library_book"."updated" FROM "library_book" INNER JOIN "library_inventory" ON ("library_book"."id" = "library_inventory"."book_id") INNER JOIN "auth_user" ON ("library_inventory"."user_id" = "auth_user"."id") INNER JOIN "library_profile" ON ("auth_user"."id" = "library_profile"."user_id") WHERE ("library_profile"."vacation" = False  AND "library_profile"."country" = BR )

具有链接的filter()调用的第一个查询集两次加入库存模型，有效地在两个条件之间创建OR，而第二个查询集与这两个条件进行AND运算.我原以为第一个查询也会对这两个条件执行AND操作.这是预期行为还是Django中的错误？

对相关问题Is there a downside to using ".filter().filter().filter()..." in Django?的回答似乎表明这两个查询集应该是等价的.