MULE_INTERNAL translation to win1250

Hi.

I have a strange problem in postgres 8.1.4 (gentoo 64bit on AMD64
platform)

My database is created vith LATIN-2 encoding for correct vieving of
nacional specific characters ( czech language )

inside code of my php application is setting client encoding to win1250
because I need output of query in this encoding.

On some parts of data I got an error :

Query failed: ERROR: character 0x829a of encoding "MULE_INTERNAL" has no
equivalent in "WIN1250"

Without "set client_encoding to win1250" query works. I am curious why there
is a MULE_INTERNAL mentioned even when \l+ say that corresponding database
is created with (and even all the cluster) LATIN2 encoding.

Strange enough that ALL INSERTS are done with WIN1250 client encoding too.
May be a bug in charset translation routines of postgres ?

And how can I repair it, preferable in whole database ?

Thanx for help.