This patch fixes not only the assertion failure in the function
Field_iterator_table_ref::set_field_iterator() but also:
- fixes the problem of forced materialization of derived tables used
in subqueries contained in WHERE clauses of single-table and multi-table
UPDATE and DELETE statements
- fixes the problem of MDEV-17954 that prevented execution of multi-table
DELETE statements if they use in their WHERE clauses references to
the tables that are updated.
The patch must be considered a complement to the patch for MDEV-28883.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
