title: 'Permission' instance expected, got ... Permission instance?
body: <p>I try to write data migration code for custom user type but when I try to apply migration I get this:</p>
  
  <pre><code>TypeError: 'Permission' instance expected, got &lt;Permission: my_app | Some Text | Can add some_model&gt;
  </code></pre>
  
  <p>Looks weird to me. Isn't that a Permission instance? Here is my custom user model:</p>
  
  <pre><code>class Employee(AbstractUser):
      middle_name = models.CharField(max_length=60, null=True, blank=True)
  </code></pre>
  
  <p>And here is a piece of code in migration which raises this error (I guess so):</p>
  
  <pre><code>for user in User.objects.all():
      employee = orm.Employee.objects.create(
      id=user.id,
      username=user.username,
      first_name=user.first_name,
      last_name=user.last_name,
      password=user.password,
      email=user.email,
  
      is_active=user.is_active,
      is_superuser=user.is_superuser,
      last_login=user.last_login,
      date_joined=user.date_joined,
      )
      for perm in user.user_permissions.all():
          employee.user_permissions.add(perm)
  </code></pre>