Description:
Using the scenario described in Bug#85559, It is possible to issue the following statement:
mysql [localhost] {root} ((none)) > set default role donald_duck to u_test_ro;
Query OK, 0 rows affected (0.01 sec)
mysql [localhost] {root} ((none)) > use mysql
Reading table information for completion of table and column names
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Database changed
mysql [localhost] {root} (mysql) > select * from mysql.default_roles;
+------+-----------+-------------------+-------------------+
| HOST | USER | DEFAULT_ROLE_HOST | DEFAULT_ROLE_USER |
+------+-----------+-------------------+-------------------+
| % | u_test_ro | % | donald_duck |
| % | u_test_rw | % | r_test_ro |
| % | u_test_rw | % | r_test_rw |
+------+-----------+-------------------+-------------------+
3 rows in set (0.00 sec)
Notice that there is no user or role named 'donald_duck'.
mysql [localhost] {root} ((none)) > select count(*) from mysql.user where user = 'donald_duck';
+----------+
| count(*) |
+----------+
| 0 |
+----------+
1 row in set (0.00 sec)
How to repeat:
Try assigning as default role a non existing one
