Hi! Thank you very much for your fixes!

I squashed all of your 4 commits and added some minor changes:
— Fixed indentation in session.c for switch statement
— Removed computation of string length from OP_Set since in struct Mem we have
int n;			/* size (in bytes) of string value, excluding trailing '\0' */

branch: https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-search-settings <https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-search-settings>
issue #1: https://github.com/tarantool/tarantool/issues/4711 <https://github.com/tarantool/tarantool/issues/4711>
issue #2: https://github.com/tarantool/tarantool/issues/4712 <https://github.com/tarantool/tarantool/issues/4712>