[1.7.x] Fix __latest__ to actually resolve to the latest migration

django/db/migrations/loader.py

@@ -155,7 +155,7 @@ class MigrationLoader(object):
                 if key[1] == "__first__":
                     return list(self.graph.root_nodes(key[0]))[0]
                 else:
-                    return list(self.graph.root_nodes(key[0]))[-1]
+                    return list(self.graph.leaf_nodes(key[0]))[0]
             except IndexError:
                 if self.ignore_no_migrations:
                     return None

tests/migrations/test_loader.py

@@ -122,6 +122,26 @@ class LoaderTests(TestCase):
             ],
         )
 
+    @modify_settings(INSTALLED_APPS={'append': 'basic'})
+    @override_settings(MIGRATION_MODULES={
+        "migrations": "migrations.test_migrations_latest",
+        "basic": "migrations.test_migrations_latest_basic",
+    })
+    def test_latest(self):
+        """
+        Makes sure that __latest__ works correctly.
+        """
+        # Load and test the plan
+        migration_loader = MigrationLoader(connection)
+        self.assertEqual(
+            migration_loader.graph.forwards_plan(("migrations", "0001_initial")),
+            [
+                ("basic", "0001_initial"),
+                ("basic", "0002_second"),
+                ("migrations", "0001_initial"),
+            ],
+        )
+
     @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
     def test_name_match(self):
         "Tests prefix name matching"

tests/migrations/test_migrations_latest/0001_initial.py

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("basic", "__latest__"),
+    ]
+
+    operations = []

tests/migrations/test_migrations_latest_basic/0001_initial.py

@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = []
+
+    operations = []

tests/migrations/test_migrations_latest_basic/0002_second.py

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("basic", "0001_initial"),
+    ]
+
+    operations = []