Mysql 5.5 to Mysql 5.6 upgrade Insert query is breaking Assume column with the following definition

product_id      INT   NULL     NO_DEFAULT
product_id_nn   INT   NOT NULL NO_DEFAULT


and query

insert into table (product_id,product_id_nn) values ('','')


the above query works in Mysql 5.5. it will insert NULL value for product_id and0for product_id_nn.

the same query breaks in Mysql 5.6 and informs you that wrong type data is getting passed. 

Yes, I am 100% accepting Mysql 5.6 statement, however why it was working in 5.5 and as you expect it's huge old php application breaking the functionality with 5.6

Any setting to make it work like 5.5?
in 5.6.12:  (Well, not really an answer, but more info.)

mysql&gt; insert into se108833 (product_id,product_id_nn) values ('','');
Query OK, 1 row affected, 2 warnings (0.00 sec)

mysql&gt; show warnings;
+---------+------+-----------------------------------------------------------------+
| Level   | Code | Message                                                         |
+---------+------+-----------------------------------------------------------------+
| Warning | 1366 | Incorrect integer value: '' for column 'product_id' at row 1    |
| Warning | 1366 | Incorrect integer value: '' for column 'product_id_nn' at row 1 |
+---------+------+-----------------------------------------------------------------+
2 rows in set (0.00 sec)

mysql&gt; select * from se108833;
+------------+---------------+
| product_id | product_id_nn |
+------------+---------------+
|          0 |             0 |
+------------+---------------+
1 row in set (0.00 sec)

mysql&gt; show variables like 'sql_mode';
+---------------+------------------------+
| Variable_name | Value                  |
+---------------+------------------------+
| sql_mode      | NO_ENGINE_SUBSTITUTION |  -- not "strict" mode
+---------------+------------------------+
1 row in set (0.00 sec)

mysql&gt; set session sql_mode = 'strict_all_tables';
Query OK, 0 rows affected (0.00 sec)

mysql&gt; insert into se108833 (product_id,product_id_nn) values ('','');
ERROR 1366 (HY000): Incorrect integer value: '' for column 'product_id' at row 1