[GENERAL] current_user changes immediately after login

Hi list,
I have a strange problem: When I connect to one of my databases, the current_user immediatly changes without any interaction from my side. This is what I do:

chschroe@db1:~> psql -h db2 testdb
Welcome to psql 8.2.5, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms

       \h for help with SQL commands
       \? for help with psql commands
       \g or terminate with semicolon to execute query
       \q to quit


testdb=> select session_user;
 session_user
--------------

testdb=> select current_user;
 current_user

How can this happen? The consequence of this is that I cannot access the tables because the role "itstaff" has no privileges. "reset role" does not have any effect. After "set role none" the current_user is equal to the session_user and the tables are accessible again.

This problem does only occur with this database. Do you have any explanation?

Regards,

    Christian

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