BUG #18763: pg_get_viewdef returns an old def with new relation name

The following bug has been logged on the website:

Bug reference: 18763
Logged by: lyz
Email address: linyuzhe(dot)lyz(at)gmail(dot)com
PostgreSQL version: 13.7
Operating system: Linux
Description:

in first connection

test5=# create table a1(c int);
CREATE TABLE
test5=# create table a2(c int);
CREATE TABLE
test5=# create view v as select * from a1;
CREATE VIEW

then rename relation names and replace view in one txn, but not commit.

test5=# begin;
BEGIN
test5=*# alter table a1 rename to a3;
ALTER TABLE
test5=*# alter table a2 rename to a1;
ALTER TABLE
test5=*# create or replace view v as select * from a1;
CREATE VIEW

in second connection:

test5=# select pg_get_viewdef('v');

it will be stuck by AccessShareLock of 'v'.

Then we commit txn in first connection,
the result of second connection wii be:

pg_get_viewdef
----------------
SELECT a3.c +
FROM a3;
(1 row)

old definition but using new relation name.