[1.11.x] Fixed #26522 -- Fixed a nondeterministic AssertionError in QuerySet combining.

Thanks Andrew Brown for the test case.

Backport of 9bbb6e2d25 from master

tests/queries/models.py

@@ -709,6 +709,11 @@ class Classroom(models.Model):
     students = models.ManyToManyField(Student, related_name='classroom')
 
 
+class Teacher(models.Model):
+    schools = models.ManyToManyField(School)
+    friends = models.ManyToManyField('self')
+
+
 class Ticket23605AParent(models.Model):
     pass