Refs #24264 -- Added failing test case for updating a FK when changing a PK

When the primary key column is altered, foreign keys of referencing
models must be aware of a possible data type change as well and thus
need to be re-rendered.

Thanks Tim Graham for the report.

tests/migrations/migrations_test_apps/alter_fk/author_app/migrations/0001_initial.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Author',
+            fields=[
+                ('id', models.AutoField(serialize=False, auto_created=True, primary_key=True)),
+                ('name', models.CharField(max_length=50)),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/alter_fk/author_app/migrations/0002_alter_id.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('author_app', '0001_initial'),
+        ('book_app', '0001_initial'),  # Forces the book table to alter the FK
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='author',
+            name='id',
+            field=models.CharField(max_length=10, primary_key=True),
+        ),
+    ]

tests/migrations/migrations_test_apps/alter_fk/book_app/migrations/0001_initial.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('author_app', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Book',
+            fields=[
+                ('id', models.AutoField(serialize=False, auto_created=True, primary_key=True)),
+                ('title', models.CharField(max_length=50)),
+                ('author', models.ForeignKey('author_app.Author')),
+            ],
+        ),
+    ]