Unable to login when user name contains unicode symbols

Hi,

 Moved from 7.1 to 7.3 recently. Database encoding is UTF-8.
 Using swing application to access database. Everything works fine -
data is displayed and updated correctly with no trouble.
 The real problem is that there is one database user name that contains
double byte character, and I'm not able to connect to database using
this user name, i.e. get exception that user does not exist. Tried
creating other users with multi-byte characters - similar problem.
 On 7.1 users with such names were able to connect to database.
 Is there a solution for this problem?
 Tried passing user name to JDBC login command as it is entered into
entry field. Then tried to pass explicitly utf-8 encoded string. Didn't
help.
 What I'm doing wrong?
 Passwords with multi-byte symbols work well, other data is inserted and
retrieved well without any external conversions. Are user names
restricted to ASCII encoding?
 Tried using both psql73jdbc2.jar and psql73jdbc3.jar drivers.

Vytautas Tolocka