Description:
------------
It appears that explode() returns an empty array (instead of an array with string in it) if limit is negative and delimiter contains a value that is not contained in string.

The documentation of explode() (http://www.php.net/manual/en/function.explode.php, section "Return Values") however states that "If delimiter contains a value that is not contained in string, then explode() will return an array containing string", which then does not hold for negative limits.

Reproduce code:
---------------
<?php 
  print_r(explode('_', 'test', -1));
  print_r(explode('_', 'test_underscore', -1));

  print_r(explode('_', 'test'));
  print_r(explode('_', 'test_underscore'));
?>

Expected result:
----------------
Array
(
    [0] => test
)
Array
(
    [0] => test
)
Array
(
    [0] => test
)
Array
(
    [0] => test
    [1] => underscore
)

Actual result:
--------------
bwiberg@musica-lp02:~$ php -n -f test.php 
Array
(
)
Array
(
    [0] => test
)
Array
(
    [0] => test
)
Array
(
    [0] => test
    [1] => underscore
)