BUG #1576: Function UPPER does not give back the awaited results

The following bug has been logged online:

Bug reference: 1576
Logged by: Sergio Luis Snchez
Email address: sluis(at)tissat(dot)es
PostgreSQL version: 7.4.3 and 8.0.1
Operating system: linux (7.4.3) and WinXP (8.0.1)
Description: Function UPPER does not give back the awaited results
Details:

Hi.

I'm from Spain, and I am using a PostgreSQL as database system. Sorry for my
English.

I launch a select with the upper function to retrieve a text in capital
letters. When I launch the function to text with accents (Usual in Spanish
language), I get the marked words in lowercase, and it's wrong.

To test it I launh this query:

select upper('aeiou');

And the result was: "AEIOU", when it must be
"AEIOU".

I try this function with UNICODE and LATIN1 encodings, and I retrieve same
result.

I reproduce the error in this two versions of Postgres:
- PostgreSQL 7.4.3 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.2.3
20030502 (Red Hat Linux 3.2.3-24)
- PostgreSQL 8.0.1 on i686-pc-mingw32, compiled by GCC gcc.exe (GCC) 3.4.2
(mingw-special)

NOTE: lower function fails too with marked words.

Thanks in advance