Parsed test spec with 2 sessions

starting permutation: s1-register s2-lock s1-lock s2-wrong-cancel-1 s2-wrong-cancel-2 s2-cancel
step s1-register:
 INSERT INTO cancel_table VALUES (pg_backend_pid(), get_cancellation_key());

step s2-lock:
	BEGIN;
	LOCK TABLE cancel_table IN ACCESS EXCLUSIVE MODE;

step s1-lock:
 BEGIN;
	LOCK TABLE cancel_table IN ACCESS EXCLUSIVE MODE;
 END;
 <waiting ...>
step s2-wrong-cancel-1: 
	SELECT run_pg_send_cancellation(pid + 1, cancel_key) FROM cancel_table;

run_pg_send_cancellation
---------------------------------------------------------------------

(1 row)

step s2-wrong-cancel-2:
	SELECT run_pg_send_cancellation(pid, cancel_key + 1) FROM cancel_table;

run_pg_send_cancellation
---------------------------------------------------------------------

(1 row)

step s2-cancel:
	SELECT run_pg_send_cancellation(pid, cancel_key) FROM cancel_table;
 END;

run_pg_send_cancellation
---------------------------------------------------------------------

(1 row)

step s1-lock: <... completed>
ERROR:  canceling statement due to user request