Encoding trouble in page versions (on Postgresql)

То reproduce:
1) Create new page.
2) Add string: Тест русский.
3) Save the page.
4) Add string: Тест русский.
5) And save the page again.

Then try to view first version.
It should contain: "5AB @CAA:89.

This trouble appears when I use PostgreSQL database, but all works fine with HSQLDB.

I test it on Postgresql v8.4 and v9.1, with JDBC v8.4 and v9.1. I create database with unicode support.
I try with and without thouse hibernate properties:

<property name="connection.useUnicode">true</property>
<property name="characterEncoding">UTF-8</property>
<property name="connection.characterSetResults">UTF-8</property>

Server locale:

LC_ALL=en_US.UTF-8
LANG=en_US.UTF-8