[1.7.x] Fixed #22861: Internal migrations done first so __first__ works

Thanks to Chris Beaven.

tests/migrations/test_graph.py

@@ -51,11 +51,11 @@ class GraphTests(TestCase):
         # Test roots and leaves
         self.assertEqual(
             graph.root_nodes(),
-            set([('app_a', '0001'), ('app_b', '0001')]),
+            [('app_a', '0001'), ('app_b', '0001')],
         )
         self.assertEqual(
             graph.leaf_nodes(),
-            set([('app_a', '0004'), ('app_b', '0002')]),
+            [('app_a', '0004'), ('app_b', '0002')],
         )
 
     def test_complex_graph(self):
@@ -105,11 +105,11 @@ class GraphTests(TestCase):
         # Test roots and leaves
         self.assertEqual(
             graph.root_nodes(),
-            set([('app_a', '0001'), ('app_b', '0001'), ('app_c', '0001')]),
+            [('app_a', '0001'), ('app_b', '0001'), ('app_c', '0001')],
         )
         self.assertEqual(
             graph.leaf_nodes(),
-            set([('app_a', '0004'), ('app_b', '0002'), ('app_c', '0002')]),
+            [('app_a', '0004'), ('app_b', '0002'), ('app_c', '0002')],
         )
 
     def test_circular_graph(self):

tests/migrations/test_loader.py

@@ -142,6 +142,26 @@ class LoaderTests(TestCase):
             ],
         )
 
+    @override_settings(MIGRATION_MODULES={
+        "migrations": "migrations.test_migrations_first",
+        "migrations2": "migrations2.test_migrations_2_first",
+    })
+    @modify_settings(INSTALLED_APPS={'append': 'migrations2'})
+    def test_first(self):
+        """
+        Makes sure the '__first__' migrations build correctly.
+        """
+        migration_loader = MigrationLoader(connection)
+        self.assertEqual(
+            migration_loader.graph.forwards_plan(("migrations", "second")),
+            [
+                ("migrations", "thefirst"),
+                ("migrations2", "0001_initial"),
+                ("migrations2", "0002_second"),
+                ("migrations", "second"),
+            ],
+        )
+
     @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
     def test_name_match(self):
         "Tests prefix name matching"

tests/migrations/test_migrations_first/second.py

@@ -0,0 +1,30 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("migrations", "thefirst"),
+        ("migrations2", "0002_second"),
+    ]
+
+    operations = [
+
+        migrations.DeleteModel("Tribble"),
+
+        migrations.RemoveField("Author", "silly_field"),
+
+        migrations.AddField("Author", "rating", models.IntegerField(default=0)),
+
+        migrations.CreateModel(
+            "Book",
+            [
+                ("id", models.AutoField(primary_key=True)),
+                ("author", models.ForeignKey("migrations.Author", null=True)),
+            ],
+        )
+
+    ]

tests/migrations/test_migrations_first/thefirst.py

@@ -0,0 +1,30 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    operations = [
+
+        migrations.CreateModel(
+            "Author",
+            [
+                ("id", models.AutoField(primary_key=True)),
+                ("name", models.CharField(max_length=255)),
+                ("slug", models.SlugField(null=True)),
+                ("age", models.IntegerField(default=0)),
+                ("silly_field", models.BooleanField(default=False)),
+            ],
+        ),
+
+        migrations.CreateModel(
+            "Tribble",
+            [
+                ("id", models.AutoField(primary_key=True)),
+                ("fluffy", models.BooleanField(default=True)),
+            ],
+        )
+
+    ]