[2.1.x] Fixed #29749 -- Made the migrations loader ignore files starting with a…

[2.1.x] Fixed #29749 -- Made the migrations loader ignore files starting with a tilde or underscore.

Regression in 29150d5d.
Backport of 32fbccab from master

django/db/migrations/loader.py

@@ -97,7 +97,10 @@ class MigrationLoader:
                 if was_loaded:
                     reload(module)
             self.migrated_apps.add(app_config.label)
-            migration_names = {name for _, name, is_pkg in pkgutil.iter_modules(module.__path__) if not is_pkg}
+            migration_names = {
+                name for _, name, is_pkg in pkgutil.iter_modules(module.__path__)
+                if not is_pkg and name[0] not in '_~'
+            }
             # Load migrations
             for migration_name in migration_names:
                 migration_path = '%s.%s' % (module_name, migration_name)

docs/releases/2.1.2.txt

@@ -11,3 +11,6 @@ Bugfixes
 
 * Fixed a regression where nonexistent joins in ``F()`` no longer raised
   ``FieldError`` (:ticket:`29727`).
+
+* Fixed a regression where files starting with a tilde or underscore weren't
+  ignored by the migrations loader (:ticket:`29749`).

tests/migrations/test_loader.py

@@ -500,6 +500,14 @@ class LoaderTests(TestCase):
         }
         self.assertEqual(plan, expected_plan)
 
+    @override_settings(MIGRATION_MODULES={'migrations': 'migrations.test_migrations_private'})
+    def test_ignore_files(self):
+        """Files prefixed with underscore, tilde, or dot aren't loaded."""
+        loader = MigrationLoader(connection)
+        loader.load_disk()
+        migrations = [name for app, name in loader.disk_migrations if app == 'migrations']
+        self.assertEqual(migrations, ['0001_initial'])
+
 
 class PycLoaderTests(MigrationTestBase):
 

tests/migrations/test_migrations_private/0001_initial.py

+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+    pass