From dcb4ed517082d13ccf7da9bd5d16c77bcecbf139 Mon Sep 17 00:00:00 2001
From: Andrew Godwin <andrew@aeracode.org>
Date: Mon, 21 Jul 2014 10:14:00 +0100
Subject: [PATCH] Fixed #22975: Don't call rename SQL if not needed

---
 django/db/backends/schema.py        |  2 ++
 tests/migrations/test_operations.py | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/django/db/backends/schema.py b/django/db/backends/schema.py
index d4573a4be8..a82524b2a0 100644
--- a/django/db/backends/schema.py
+++ b/django/db/backends/schema.py
@@ -367,6 +367,8 @@ class BaseDatabaseSchemaEditor(object):
         """
         Renames the table a model points to.
         """
+        if old_db_table == new_db_table:
+            return
         self.execute(self.sql_rename_table % {
             "old_table": self.quote_name(old_db_table),
             "new_table": self.quote_name(new_db_table),
diff --git a/tests/migrations/test_operations.py b/tests/migrations/test_operations.py
index b8d1ae5819..7e3e030518 100644
--- a/tests/migrations/test_operations.py
+++ b/tests/migrations/test_operations.py
@@ -769,6 +769,26 @@ class OperationTests(OperationTestBase):
         self.assertTableExists("test_almota_pony")
         self.assertTableNotExists("test_almota_pony_2")
 
+    def test_alter_model_table_noop(self):
+        """
+        Tests the AlterModelTable operation if the table name is not changed.
+        """
+        project_state = self.set_up_test_model("test_almota")
+        # Test the state alteration
+        operation = migrations.AlterModelTable("Pony", "test_almota_pony")
+        new_state = project_state.clone()
+        operation.state_forwards("test_almota", new_state)
+        self.assertEqual(new_state.models["test_almota", "pony"].options["db_table"], "test_almota_pony")
+        # Test the database alteration
+        self.assertTableExists("test_almota_pony")
+        with connection.schema_editor() as editor:
+            operation.database_forwards("test_almota", editor, project_state, new_state)
+        self.assertTableExists("test_almota_pony")
+        # And test reversal
+        with connection.schema_editor() as editor:
+            operation.database_backwards("test_almota", editor, new_state, project_state)
+        self.assertTableExists("test_almota_pony")
+
     def test_alter_field(self):
         """
         Tests the AlterField operation.