BUG #19107: The hold cursor is unexpectedly released during rollback

The following bug has been logged on the website:

Bug reference: 19107
Logged by: Man Zeng
Email address: zengman(at)halodbtech(dot)com
PostgreSQL version: 18.0
Operating system: Ubuntu 24.04
Description:

Hi, hackers.

While I was writing test cases for the hold cursor, I unexpectedly
discovered that commit and rollback handle it inconsistently—rollback
unexpectedly releases the hold cursor. Should this be regarded as a bug?

--
Regrads,
Man Zeng

postgres=# -- ok
postgres=# DO $$
DECLARE
val int;
BEGIN
FOR val IN SELECT generate_series(1,10) LOOP
raise notice 'val = %', val;
IF val % 2 = 0 THEN
COMMIT;
ELSE
ROLLBACK;
END IF;
END LOOP;
END; $$;
NOTICE: val = 1
NOTICE: val = 2
NOTICE: val = 3
NOTICE: val = 4
NOTICE: val = 5
NOTICE: val = 6
NOTICE: val = 7
NOTICE: val = 8
NOTICE: val = 9
NOTICE: val = 10
DO
postgres=#
postgres=# -- hold_cursor commit ok
postgres=# do $$
declare
p_CurData refcursor := 'hold_cursor';
val int;
begin
execute 'declare hold_cursor CURSOR WITH HOLD FOR SELECT 42';
loop
fetch p_CurData into val;
exit when val is null;
raise notice 'val = %', val;
commit;
end loop;
close p_CurData;
end; $$;
NOTICE: val = 42
DO
postgres=#
postgres=# -- hold_cursor rollback error
postgres=# do $$
declare
p_CurData refcursor := 'hold_cursor';
val int;
begin
execute 'DECLARE hold_cursor CURSOR WITH HOLD FOR SELECT 42';
loop
fetch p_CurData into val;
exit when val is null;
raise notice 'val = %', val;
rollback;
end loop;
close p_CurData;
end; $$;
NOTICE: val = 42
ERROR: cursor "hold_cursor" does not exist
CONTEXT: PL/pgSQL function inline_code_block line 8 at FETCH