Comment 2 for bug 222488

i might be having the same problem:

 * Reloading PostgreSQL 8.3 database server [ OK ]
You'll see some debugging info during this installation.
Do not worry unless told otherwise.
Creating initial Sourceforge database from files.
Creating debian_meta_data table.
Inserting first data into debian_meta_data table.
Updating debian_meta_data table.
Committing.
Processing /usr/lib/gforge/db/sf-2.6-complete.sql
DETAIL: Found referencing table's trigger.
DETAIL: Found referenced table's DELETE trigger.
DETAIL: Found referenced table's UPDATE trigger.
DETAIL: Found referencing table's trigger.
DETAIL: Found referenced table's DELETE trigger.
DETAIL: Found referenced table's UPDATE trigger.
DBD::Pg::st execute failed: ERROR: constraint "forum_group_forum_id_fk" for relation "forum" already exists
Transaction aborted because DBD::Pg::st execute failed: ERROR: constraint "forum_group_forum_id_fk" for relation "forum" already exists
Transaction aborted because DBD::Pg::st execute failed: ERROR: constraint "forum_group_forum_id_fk" for relation "forum" already exists
Last SQL query was:
CREATE CONSTRAINT TRIGGER "forum_group_forum_id_fk" AFTER UPDATE ON "forum_group_list" NOT DEFERRABLE INITIALLY IMMEDIATE FOR EACH ROW EXECUTE PROCEDURE "RI_FKey_noaction_upd" ('forum_group_forum_id_fk', 'forum', 'forum_group_list', 'FULL', 'group_forum_id', 'group_forum_id');
(end of query)
Your database schema is at version 2.5.9999
Please report this bug on the Debian bug-tracking system.
Please include the previous messages as well to help debugging.
You should not worry too much about this,
your DB is still in a consistent state and should be usable.
dpkg: error processing gforge-db-postgresql (--configure):
 subprocess post-installation script returned error exit status 1
Setting up postfix-pgsql (2.5.1-2ubuntu1) ...
Adding pgsql map entry to /etc/postfix/dynamicmaps.cf

dpkg: dependency problems prevent configuration of gforge-mta-postfix:
 gforge-mta-postfix depends on gforge-db-postgresql | gforge-db; however:
  Package gforge-db-postgresql is not configured yet.
  Package gforge-db is not installed.
  Package gforge-db-postgresql which provides gforge-db is not configured yet.
dpkg: error processing gforge-mta-postfix (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 gforge-db-postgresql
 gforge-mta-postfix
E: Sub-process /usr/bin/dpkg returned an error code (1)