Civi won't send simple mails to all email recpients if some hold multiple addresses

See http://civicrm.stackexchange.com/questions/16613/civi-does-not-email-to-some-contacts-not-civimail-just-mail for an introduction...

CRM_Contact_BAO_Query::apiQuery() returns wrong rows if

• parameter $rowCount is passed
• $query's group_by isn't set and
• contacts hold more than on email addresses.

In this case dao returns multiple rows for one contact and the sql limit by $rowCount will lead to missing items.

Core folks, where to set $_useGroupBy = true? I'm confused because you call the static function apiQuery by instance $query in CRM_Utils_Toke.php. The static function itself creates an object of it's class. But because signature lacks a groupBy flag I don't know if it's save to tell the query to group by. Should it always group by here?

Jesus! What a rant.

Proposed fix: https://github.com/civicrm/civicrm-core/pull/9676 or maybe better addressed by https://github.com/civicrm/civicrm-core/pull/10915 by Eileen McNaughton