The following test is crashing the MariaDB Server 10.2 debug build in the CREATE INDEX:
The innodb_file_format and ROW_FORMAT=DYNAMIC are defaults. I added them only to test this in 10.0 and 10.1, which rightfully reported the following:
mysqltest: At line 7: query 'CREATE INDEX prefix_idx ON t(a(1000))' succeeded - should have failed with errno 1071...
In 10.2 we instead get the famous debug assertion failure:
mysqld: /mariadb/10.2/sql/sql_error.cc:380: void Diagnostics_area::set_ok_status(ulonglong, ulonglong, const char *): Assertion `!is_set() || (m_status == DA_OK_BULK && is_bulk_op())' failed.