Description:
------------
In php 5.5, using the ?: operator in reference based foreach loops worked. In php 7.1 the reference doesn't affect the original array any more.

Test script:
---------------
<?php

$a=['hello' => [1,2,3]];

foreach ($a['hello'] ?: [] as &$x)
    $x++;

print_r($a);


Expected result:
----------------
In PHP 5.5 and PHP 5.6 the output is:

Array
(
    [hello] => Array
        (
            [0] => 2
            [1] => 3
            [2] => 4
        )

)


Actual result:
--------------
In PHP 7.1 the output is:

Array
(
    [hello] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
        )

)