Fixed #25239 -- Corrected makemigrations numbering if a migration has a number-only filename.

django/db/migrations/autodetector.py

@@ -1154,6 +1154,7 @@ class MigrationAutodetector(object):
         Given a migration name, tries to extract a number from the
         beginning of it. If no number found, returns None.
         """
-        if re.match(r"^\d+_", name):
+        match = re.match(r'^\d+', name)
-            return int(name.split("_")[0])
+        if match:
+            return int(match.group())
         return None

tests/migrations/test_commands.py

@@ -510,6 +510,19 @@ class MakeMigrationsTests(MigrationTestBase):
                     self.assertIn('\\xda\\xd1\\xcd\\xa2\\xd3\\xd0\\xc9', content)  # title.verbose_name
                     self.assertIn('\\u201c\\xd0j\\xe1\\xf1g\\xf3\\u201d', content)  # title.default
 
+    def test_makemigrations_order(self):
+        """
+        makemigrations should recognize number-only migrations (0001.py).
+        """
+        module = 'migrations.test_migrations_order'
+        with self.temporary_migration_module(module=module) as migration_dir:
+            if hasattr(importlib, 'invalidate_caches'):
+                # Python 3 importlib caches os.listdir() on some platforms like
+                # Mac OS X (#23850).
+                importlib.invalidate_caches()
+            call_command('makemigrations', 'migrations', '--empty', '-n', 'a', '-v', '0')
+            self.assertTrue(os.path.exists(os.path.join(migration_dir, '0002_a.py')))
+
     def test_failing_migration(self):
         # If a migration fails to serialize, it shouldn't generate an empty file. #21280
         apps.register_model('migrations', UnserializableModel)

tests/migrations/test_migrations_order/0001.py

@@ -0,0 +1,12 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    operations = [
+    ]