Fixed #24675 -- Skipped SQL_AUTO_IS_NULL query on MySQL if not needed.

tests/backends/test_mysql.py

@@ -0,0 +1,20 @@
+from __future__ import unicode_literals
+
+import unittest
+
+from django.db import connection
+from django.test import TestCase, override_settings
+
+
+@override_settings(DEBUG=True)
+@unittest.skipUnless(connection.vendor == 'mysql', 'MySQL specific test.')
+class MySQLTests(TestCase):
+
+    def test_auto_is_null_auto_config(self):
+        query = 'set sql_auto_is_null = 0'
+        connection.init_connection_state()
+        last_query = connection.queries[-1]['sql'].lower()
+        if connection.features.is_sql_auto_is_null_enabled:
+            self.assertIn(query, last_query)
+        else:
+            self.assertNotIn(query, last_query)