Description:
------------
The code and results attached show two examples of preg_* demonstrating how an optional parenthesis match at the end of a regular expression is not being captured if the optional condition is not matched.

I think this is a bug, because if the optional parenthesis is not the last one in the regex, the empty value IS captured - which suggests that it should not be omitted just because it happens to be the last one.


Reproduce code:
---------------
preg_match_all("/(1)(23)?/", "12314123", $match, PREG_SET_ORDER);
print_r($match);
print_r(preg_split("/(1)(23)?/", "12314123", -1, PREG_SPLIT_DELIM_CAPTURE));


Expected result:
----------------
Array
(
    [0] => Array
        (
            [0] => 123
            [1] => 1
            [2] => 23
        )

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

    [2] => Array
        (
            [0] => 123
            [1] => 1
            [2] => 23
        )

)
Array
(
    [0] => 
    [1] => 1
    [2] => 23
    [3] => 
    [4] => 1
    [5] => 
    [6] => 4
    [7] => 1
    [8] => 23
    [9] => 
)


Actual result:
--------------
Array
(
    [0] => Array
        (
            [0] => 123
            [1] => 1
            [2] => 23
        )

    [1] => Array
        (
            [0] => 1
            [1] => 1
        )

    [2] => Array
        (
            [0] => 123
            [1] => 1
            [2] => 23
        )

)
Array
(
    [0] => 
    [1] => 1
    [2] => 23
    [3] => 
    [4] => 1
    [5] => 4
    [6] => 1
    [7] => 23
    [8] => 
)