Add a test for #7039

tests/queries/0_stateless/01550_mutation_subquery.reference

+1	2
+---

tests/queries/0_stateless/01550_mutation_subquery.sql

+DROP TABLE IF EXISTS t;
+
+CREATE TABLE t(`id` String, `dealer_id` String) ENGINE = MergeTree() ORDER BY id SETTINGS index_granularity = 8192;
+insert into t(id, dealer_id) values('1','2');
+SELECT * FROM t;
+SET mutations_sync = 1;
+ALTER TABLE t DELETE WHERE id in (select id from t as tmp);
+SELECT '---';
+SELECT * FROM t;
+
+DROP TABLE t;