MDL-10970 Someone was using

MDL-10970 Someone was using
$locations = array('location1');
$locations += array('location2', 'location3', 'location4');

to save the hassle of doing one $locations[] = 'location1'; for each location.

But += doesn't add any entry if the key of the new array already exists in the original array. So, using my example, the resulting array would be:

$locations: array('location1', 'location3', 'location4');