Description:
------------
Unexpected results returned when using positioned parameters in sscanf()

Reproduce code:
---------------
$test = sscanf('test string', '%2$s %1$s');
print_r($test);

Expected result:
----------------
array(
   [0] => 'string',
   [1] => 'test'
)

Actual result:
--------------
Array
(
    [0] => 
    [1] => 
    [3] => test
    [2] => string
)