BUG #11550: Error messages contain not encodable characters (Latin9)

The following bug has been logged on the website:

Bug reference:      11550
Logged by:          Walter W.
Email address:      willmis@gmail.com
PostgreSQL version: 9.3.5
Operating system:   Linux/Windows
Description:

In 9.3 we have new characters for delimiting words.

An example:
"Drop table if exists mickeymouse;"
delivers in PG-9.3

HINWEIS: Tabelle „mickeymouse“ existiert nicht, wird übersprungen

but delivers in PG-8.4

HINWEIS: Tabelle »mickeymouse« existiert nicht, wird übersprungen

If we set client_encoding to Latin9 (as we are here in Germany), we get an
error message from PostgreSQL:

character with byte sequence 0xe2 0x80 0x9e in encoding UTF8 has no
equivalent in LATIN9

This behaviour leads to problems in tools we use like Zeos etc.

Is there a way to change the delimiters in messages by some way?
This would help us a lot.