PostgreSQL: error with group by when adding/saving a node.

PostgreSQL install, Drupal 6.22 (and previous versions).

This is apparently quite similar on 7.x (https://drupal.org/node/1348764) But I'm seeing it on 6x.-1.4.

Error:
query: INSERT INTO subscriptions_queue (uid, name, language, module, field, value, author_uid, send_interval, digest, last_sent, load_function, load_args, is_new, suspended) SELECT u.uid, u.name, u.language, s.module, s.field, s.value, s.author_uid, s.send_interval, su.digest, COALESCE(sls.last_sent, 0), 'subscriptions_content_node_load', '4699', '0', suspended FROM subscriptions s INNER JOIN subscriptions_user su ON s.recipient_uid = su.uid INNER JOIN users u ON su.uid = u.uid INNER JOIN term_node tn ON s.value = CAST(tn.tid AS VARCHAR) LEFT JOIN subscriptions_last_sent sls ON su.uid = sls.uid AND s.send_interval = sls.send_interval WHERE s.module = 'node' AND s.field = 'tid' AND s.author_uid IN (2, -1) AND tn.nid = 4699 AND s.send_updates = 1 GROUP BY u.uid, tn.nid in /(path)/sites/all/modules/subscriptions/subscriptions.module on line 332.

with followup error message:

pg_query(): Query failed: ERROR: column "s.module" must appear in the GROUP BY clause or be used in an aggregate function LINE 3: SELECT u.uid, u.name, u.language, s.module, s.fiel... ^ in /(path)/includes/database.pgsql.inc on line 138.

So I dug around for the Group By and found the subscriptions_taxonomy.module line 36 has this:

'groupby' => 'GROUP BY u.uid, tn.nid',

Changing it to:
'groupby' => 'GROUP BY u.uid, tn.nid, s.module, s.field, s.value, s.author_id, s.send_interval',

Eliminates the error.

Anything short of those fields generates an error asking for the missing fields to be in the Group By.

I can't tell if this breaks the SQL or anything based on the fact that I don't have a user subscribed to that taxonomy right now, I don't think, but it has stopped the error and is not generating new ones. It was just an error I wanted to get rid of.