Problem with perl DBI => postgress after upgrade

[Aart Koelewijn]

I run a home-written perl program to fill a postgres database with 
measurements. In this program I have the line:

$dbh = DBI->connect("dbi:Pg:dbname=$dbname;host=$host","","");

This always worked fine. Since I upgraded my box from Ubuntu 10.04 to 
10.10 this afternoon, when I try to run the program I get:

DBI connect('dbname=bluetooth;host=mtack3','',...) failed: fe_sendauth: 
no password supplied at bin/bttracking.pl line 62
Can't call method "prepare" on an undefined value at bin/bttracking.pl 
line 63.

I tried supplying a password in the above line, but still could not 
connect. Connecting to the database from a shell with "psql -d dbname" 
works fine, no need to supply a password. I read and reread perldoc DBI, 
but could not find a solution.

Anybody got any ideas what I can try next?

Aart