Invalid PostgreSQL syntax creating new vocabulary for Forums

When accessing "Administer >> Forums" for the first time, Drupal tries to automatically create a new vocabulary for Forums. An error results and the new vocabulary is not created:

warning: pg_query(): Query failed: ERROR: invalid input syntax for integer: "" in /var/www/drupal/includes/database.pgsql.inc on line 45.
user error:
query: INSERT INTO vocabulary (name, description, help, multiple, required, hierarchy, relations, weight, module, vid) VALUES ('Forums', '', '', 0, 1, 1, 0, '', 'forum', '1') in /var/www/drupal/includes/database.pgsql.inc on line 62.

It turns out the "weight" attribute of the vocabulary table is an integer and PostgreSQL does not allow inserting the null string into an Integer. Manually running the SQL but using '0' instead of '' solved the problem for me.