Assertion failure in smgr.c when using pg_prewarm with partitioned tables

Hi,

I encountered an assertion failure when a partitioned table is specified
as an argument to pg_prewarm. Below are the steps to reproduce the
issue:

$ pgbench -i -s 1 --partitions=3
$ psql <<EOF
CREATE EXTENSION pg_prewarm;
SELECT pg_prewarm('pgbench_accounts');
EOF

The following assertion failure occurs:

TRAP: failed Assert("RelFileNumberIsValid(rlocator.relNumber)"), File:
"smgr.c", Line: 246, PID: 1246282
postgres: ikeda postgres [local]
SELECT(ExceptionalCondition+0xbb)[0x55edd16725c1]
postgres: ikeda postgres [local] SELECT(smgropen+0x5e)[0x55edd145c1ff]

It looks like this may have been overlooked in commit 049ef33.
What do you think?

Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION