Fixed #24184 -- Prevented automatic soft-apply of migrations

Previously Django only checked for the table name in CreateModel
operations in initial migrations and faked the migration automatically.
This led to various errors and unexpected behavior. The newly introduced
--fake-initial flag to the migrate command must be passed to get the
same behavior again. With this change Django will bail out in with a
"duplicate relation / table" error instead.

Thanks Carl Meyer and Tim Graham for the documentation update, report
and review.

2 files changed, 16 insertions, 9 deletions

diff --git a/django/core/management/commands/migrate.py b/django/core/management/commands/migrate.py
index d1aff756f0..5dc7dc00f7 100644
--- a/django/core/management/commands/migrate.py
+++ b/django/core/management/commands/migrate.py
@@ -40,6 +40,10 @@ class Command(BaseCommand):
                 'Defaults to the "default" database.')
         parser.add_argument('--fake', action='store_true', dest='fake', default=False,
             help='Mark migrations as run without actually running them')
+        parser.add_argument('--fake-initial', action='store_true', dest='fake_initial', default=False,
+            help='Detect if tables already exist and fake-apply initial migrations if so. Make sure '
+                 'that the current database schema matches your initial migration before using this '
+                 'flag. Django will only check for an existing table name.')
         parser.add_argument('--list', '-l', action='store_true', dest='list', default=False,
             help='Show a list of all known migrations and which are applied')
 
@@ -186,7 +190,9 @@ class Command(BaseCommand):
                         "apply them."
                     ))
         else:
-            executor.migrate(targets, plan, fake=options.get("fake", False))
+            fake = options.get("fake")
+            fake_initial = options.get("fake_initial")
+            executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
 
         # Send the post_migrate signal, so individual apps can do whatever they need
         # to do at this point.
diff --git a/django/db/migrations/executor.py b/django/db/migrations/executor.py
index 8a55ed0d69..d1a8dd64dc 100644
--- a/django/db/migrations/executor.py
+++ b/django/db/migrations/executor.py
@@ -62,7 +62,7 @@ class MigrationExecutor(object):
                         applied.add(migration)
         return plan
 
-    def migrate(self, targets, plan=None, fake=False):
+    def migrate(self, targets, plan=None, fake=False, fake_initial=False):
         """
         Migrates the database up to the given targets.
 
@@ -91,7 +91,7 @@ class MigrationExecutor(object):
         # Phase 2 -- Run the migrations
         for migration, backwards in plan:
             if not backwards:
-                self.apply_migration(states[migration], migration, fake=fake)
+                self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial)
             else:
                 self.unapply_migration(states[migration], migration, fake=fake)
 
@@ -113,18 +113,19 @@ class MigrationExecutor(object):
             statements.extend(schema_editor.collected_sql)
         return statements
 
-    def apply_migration(self, state, migration, fake=False):
+    def apply_migration(self, state, migration, fake=False, fake_initial=False):
         """
         Runs a migration forwards.
         """
         if self.progress_callback:
             self.progress_callback("apply_start", migration, fake)
         if not fake:
-            # Test to see if this is an already-applied initial migration
-            applied, state = self.detect_soft_applied(state, migration)
-            if applied:
-                fake = True
-            else:
+            if fake_initial:
+                # Test to see if this is an already-applied initial migration
+                applied, state = self.detect_soft_applied(state, migration)
+                if applied:
+                    fake = True
+            if not fake:
                 # Alright, do it normally
                 with self.connection.schema_editor() as schema_editor:
                     state = migration.apply(state, schema_editor)