[1.10.x] Fixed #27180 -- Fixed a crash in MySQL checks where SELECT @@sql_mode doesn't return a result.

Backport of 2b64ff68cc from master

django/db/backends/mysql/validation.py

@@ -13,7 +13,7 @@ class DatabaseValidation(BaseDatabaseValidation):
         with self.connection.cursor() as cursor:
             cursor.execute("SELECT @@sql_mode")
             sql_mode = cursor.fetchone()
-        modes = set(sql_mode[0].split(','))
+        modes = set(sql_mode[0].split(',') if sql_mode else ())
         if not (modes & {'STRICT_TRANS_TABLES', 'STRICT_ALL_TABLES'}):
             return [checks.Warning(
                 "MySQL Strict Mode is not set for database connection '%s'" % self.connection.alias,

docs/releases/1.10.2.txt

@@ -9,4 +9,5 @@ Django 1.10.2 fixes several bugs in 1.10.1.
 Bugfixes
 ========
 
-* ...
+* Fixed a crash in MySQL database validation where ``SELECT @@sql_mode``
+  doesn't return a result (:ticket:`27180`).