Description:
------------
this is similar to #50816

but not quite same. 



Test script:
---------------
define("FIRST_KEY", "a");
define("THIRD_KEY", "c");

function test()
{
        static $arr = array(
                "a" => "222",
                FIRST_KEY => "111",
                "c" => "333",
                THIRD_KEY => "444",
        );
        print_r($arr);
}

test();

Expected result:
----------------
Array
(
    [a] => 111
    [c] => 444
)

Actual result:
--------------
Array
(
    [a] => 222
    [c] => 444
)