`sql_mode` is always strict

[pbowyer]

I have a query failing with ERROR 1105 (HY000): expression 'Policy.data' doesn't appear in the group by expressions. With legacy systems normally I relax sql_mode to TRADITIONAL or "" to get round this, which works perfectly on MySQL. With Dolt I can change the value of sql_mode but it doesn't have any effect on the way the queries run.

The erroring query:

SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data 
FROM `access_resource_groups` Acl 
LEFT JOIN `access_policies` Policy ON Policy.id = Acl.policy 
JOIN `document_groups` ResourceGroup ON Acl.principal_class = 'modUserGroup' 
AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') 
AND ResourceGroup.document = '26714' 
AND ResourceGroup.document_group = Acl.target 
GROUP BY Acl.target, Acl.principal, Acl.authority, Acl.policy

Sample session:

mysql> set sql_mode='';
Query OK, 1 row affected (0.01 sec)

mysql> select @@sql_mode;
+--------------------+
| @@SESSION.sql_mode |
+--------------------+
|                    |
+--------------------+
1 row in set (0.01 sec)

mysql> SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `access_resource_groups` Acl LEFT JOIN `access_policies` Policy ON Policy.id = Acl.policy JOIN `document_groups` ResourceGroup ON Acl.principal_class = 'modUserGroup' AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') AND ResourceGroup.document = '26714' AND ResourceGroup.document_group = Acl.target GROUP BY Acl.target, Acl.principal, Acl.authority, Acl.policy;
ERROR 1105 (HY000): expression 'Policy.data' doesn't appear in the group by expressions
mysql> set sql_mode='TRADITIONAL';
Query OK, 1 row affected (0.01 sec)

mysql> select @@sql_mode;
+--------------------+
| @@SESSION.sql_mode |
+--------------------+
| TRADITIONAL        |
+--------------------+
1 row in set (0.01 sec)

mysql> SELECT Acl.target, Acl.principal, Acl.authority, Acl.policy, Policy.data FROM `access_resource_groups` Acl LEFT JOIN `access_policies` Policy ON Policy.id = Acl.policy JOIN `document_groups` ResourceGroup ON Acl.principal_class = 'modUserGroup' AND (Acl.context_key = 'web' OR Acl.context_key IS NULL OR Acl.context_key = '') AND ResourceGroup.document = '26714' AND ResourceGroup.document_group = Acl.target GROUP BY Acl.target, Acl.principal, Acl.authority, Acl.policy;
ERROR 1105 (HY000): expression 'Policy.data' doesn't appear in the group by expressions

[pbowyer]

Related: #2172

[timsehn]

Closing in favor of #2172