Unexpected result when using IS DISTINCT FROM

[suyZhong]

Describe the bug
The IS DISTINCT FROM operator in MonetDB returns unexpected results when used with NULL. Specifically, the negation of NULL IS DISTINCT FROM NULL returns NULL instead of true.

To Reproduce

SELECT (NULL IS DISTINCT FROM NULL); -- false
SELECT NOT (NULL IS DISTINCT FROM NULL); -- null (unexpected)

Expected behavior
As mentioned above.

Screenshots
N/A

Software versions
Build from source:

> docker exec -it monetdb-test mserver5 --version         
MonetDB 5 server 11.50.0 (hg id: 6e3d6f5) (64-bit, 128-bit integers)
This is an unreleased version
Copyright (c) 1993 - July 2008 CWI
Copyright (c) August 2008 - 2023 MonetDB B.V., all rights reserved
Visit https://www.monetdb.org/ for further information
Found 503.5GiB available memory, 128 available cpu cores
Libraries:
Compiled by: @7094a4ca4432 (x86_64-pc-linux-gnu)
Compilation: /usr/bin/cc 
Linking    : /usr/bin/ld

Issue labeling
Bug

Additional context
Add any other context about the problem here.

[aris-koning]

Hi, thanks for reporting. It should be fixed on hg:3a51d8edf6af.