OgMembership::save() does not update entity audience field

[schultetwin]

To set context, I have a module that generates a node from an incoming email and associates it with a group based on the email address that it came in on. The flow looks something like this:

//(email arrives, and triggers drupal)
// Prepare node, populate fields
node_save($node);
foreach ($group_nodes as $gid => $group_node) {
  og_group('node', $gid, array('entity_type' => 'node', 'entity' => $node);
}
// At this point, $node->og_group_ref should be populated, but it is not.

(FYI, this is a modification I'm making to the og_mailinglist module).

In the og_group() source code, it specifically mentions that OgMembership::save() should update the entity in question.

My current solution is this:

    $entity_wrapper = entity_metadata_wrapper($entity_type, $entity);
    $items = $entity_wrapper->{$field_name}->value();
    $items[] = $group;
    $entity_wrapper->{$field_name}->set($items);

In OgMembership::save() after parent::save(). (Sorry, no patch at the moment).

[schultetwin]

Updated sample solution to something that actually works.