There is currently a hack that makes a custom string to pass on to the adodb layer, "aggregating" the username, password, host and dbname, for postgresql. This is not necessary, as the adbodb doc at http://phplens.com/lens/adodb/docs-adodb.htm#connect_ex explicitly states that pgsql 7 & 8 support connecting using the "four arguments".
This actually corrects a bug, occuring when the connection fails, and the user comes back to the database setup screen, with all fields empty, except for the "host", which contains the aggregated information.
Along is a patch fixing this.
As this seems to be historical (August 2004), Martin, can you confirm that it's alright to remove these lines? I tested on pgsql 8.2, but I don't have access to any older version.