BUG #16675: VALUES not working for CITEXT

The following bug has been logged on the website:

Bug reference:      16675
Logged by:          Mark Cowne
Email address:      mcowne@webroot.com
PostgreSQL version: 11.7
Operating system:   x86_64-pc-linux-gnu
Description:

-- Fourth SELECT doesn't return anything and should.

CREATE TABLE Test(Col CITEXT NOT NULL PRIMARY KEY);

INSERT INTO Test(Col) VALUES('ABC');

SELECT Col FROM Test WHERE Col IN ('abc');
SELECT Col FROM Test WHERE Col IN ('ABC');
SELECT Col FROM Test WHERE Col IN (VALUES('ABC'));
SELECT Col FROM Test WHERE Col IN (VALUES('abc'));

DROP TABLE Test;