sql_mode=ORACLE does not include STRICT_TRANS_TABLES

This problem was originally reported by Jerome Brauge:

STRICT_TRANS_TABLES is not set in sql_mode=ORACLE.
It should be. The following script should return an error:

set sql_mode=oracle;

create table t1 (c1 integer not null,c2 integer not null);

insert into t1 (c1) values(1);

Query OK, 1 row affected, 1 warning

Sergei also proposes to check if we should set additionally set TRADITIONAL when sql_mode=ORACLE.