Refs #25786 -- Added tests/release notes for set_FOO_order() crash with order_with_respect_to referencing OneToOneField pk.

Forwardport of 6d9f061b07ce7aa1a9da6799b3104971ee73998b from stable/1.8.x
The issue was fixed by 7bec480fe2ace94c8e7f0c88485442bfa74436b4.

docs/releases/1.8.7.txt

@@ -42,3 +42,7 @@ Bugfixes
 
 * Fixed a duplicate query regression in 1.8 on proxied model deletion
   (:ticket:`25685`).
+
+* Fixed ``set_FOO_order()`` crash when the ``ForeignKey`` of a model with
+  ``order_with_respect_to`` references a model with a ``OneToOneField``
+  primary key (:ticket:`25786`).

tests/order_with_respect_to/models.py

@@ -42,3 +42,19 @@ class Post(models.Model):
 
     def __str__(self):
         return self.title
+
+
+# order_with_respect_to points to a model with a OneToOneField primary key.
+class Entity(models.Model):
+    pass
+
+
+class Dimension(models.Model):
+    entity = models.OneToOneField('Entity', primary_key=True, on_delete=models.CASCADE)
+
+
+class Component(models.Model):
+    dimension = models.ForeignKey('Dimension', on_delete=models.CASCADE)
+
+    class Meta:
+        order_with_respect_to = 'dimension'

tests/order_with_respect_to/tests.py

@@ -6,7 +6,7 @@ from django.apps.registry import Apps
 from django.db import models
 from django.test import TestCase
 
-from .models import Answer, Post, Question
+from .models import Answer, Dimension, Entity, Post, Question
 
 
 class OrderWithRespectToTests(TestCase):
@@ -118,3 +118,13 @@ class OrderWithRespectToTests2(TestCase):
                 count += 1
 
         self.assertEqual(count, 1)
+
+
+class TestOrderWithRespectToOneToOnePK(TestCase):
+    def test_set_order(self):
+        e = Entity.objects.create()
+        d = Dimension.objects.create(entity=e)
+        c1 = d.component_set.create()
+        c2 = d.component_set.create()
+        d.set_component_order([c1.id, c2.id])
+        self.assertQuerysetEqual(d.component_set.all(), [c1.id, c2.id], attrgetter('pk'))