Python django角色权限不适用于事务？

我为以下问题挣扎了几天。 应用程序使用django角色权限。单元测试不能正常工作。下面是示例代码：

from django.contrib.auth.models import User
from rolepermissions.roles import AbstractUserRole


class FooRole(AbstractUserRole):
    available_permissions = {
        "foo": "bar"
    }


user = User.objects.create(username="abc")
with transaction.atomic():
    role = FooRole.assign_role_to_user(user)

运行测试时，尝试将角色分配给用户时会发生以下情况：

django.contrib.auth.models.Group.DoesNotExist: Group matching query does not exist.    
During handling of the above exception, another exception occurred:
MySQLdb._exceptions.OperationalError: (1305, 'SAVEPOINT s4598857152_x2 does not exist')

如有任何建议，将不胜感激

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