I'm concerned that this leaves nonMagicAutoCommit set to ```FALSE``` I'd like to see this function take an argument like ```$set_auto_commit``` which defaults to ```TRUE```, so that calling code can look like this:
```PHP
$object = islandora_object_load($pid);
$object->relationships->autoCommit = FALSE;
$object->relationships->add(ISLANDORA_RELS_INT_URI, $viewable_by_user, $user, TRUE);
$object->relationships->add(ISLANDORA_RELS_EXT_URI, $manageable_by_user, $user, TRUE);
$object->relationships->commitRelationships();
```
Then we would not have to set ```$object->relationships->autoCommit = TRUE;```  after doing the above, so the object would be safe for use in other hooks that are unaware of the new feature.