IF an INSERT/REPLACE SELECT statement contained an ON expression in the top
level select and this expression used a subquery with a column reference
that could not be resolved then an attempt to resolve this reference as
an outer reference caused a crash of the server. This happened because the
outer context field in the Name_resolution_context structure was not set
to NULL for such references. Rather it pointed to the first element in
the select_stack.

Note that starting from 10.4 we cannot use the SELECT_LEX::outer_select()
method when parsing a SELECT construct.

Approved by Oleksandr Byelkin <sanja@mariadb.com>