Bug in Sequences [6.4.2]

Greetings,
there seems to be a slight bug in the parsing of the
nextval function, tested under 6.4.2.
It affects also the SERIAL type.

Symptom :

CREATE SEQUENCE "AA";
-- Correct, quoted identifier is allowed;
SELECT NEXTVAL('AA');
--Produces Error
--aa.nextval: sequence does not exist


Probable source of problem, the Argument to nextval is
not handled correctly as an Table Identifier.

E.g. nextval('"AA"') is generates
"aa".nextval: sequence does not exist

Note the lowercase between the quotes.

I quickly browsed the sources, but have not found the
place where the conversion to lowercase occurs.

Please check this against 6.5 and 6.4.3 too.

With Regards,
    Stefan Wehner