BUG #5903: Turkish encoding problem

The following bug has been logged online:

Bug reference:      5903
Logged by:          Sarp Akal
Email address:      sarp@dms-tech.com
PostgreSQL version: 9.0.2
Operating system:   Windows Server 2008 R2 x64
Description:        Turkish encoding problem
Details:

The server is setup for UTF8 encoding and collation and character type are
Turkish_Turkey.1254

The following code fails:

select lower('Ä°')  --> Lowercase of turkish capital I-with dot returns
exactly the same character.

select upper('ı')  --> Uppercase of turkish small i-without dot returns
exactly the same character.

select lower('I')  --> Lowercase of turkish capital I returns i where it
should be i-without dot.

select upper('i')  --> Uppercase of turkish small returns I where it should
be I-with dot.