Description:
------------
array_unique() on an array with strings and the value int(0) drops int(0)

or if int(0) comes first, it drops the first string

Reproduce code:
---------------
jablko@tad:~/php5.2-200904292030$ sapi/cli/php -r 'var_dump(array_unique(array("foo", 0)));'
array(1) {
  [0]=>
  string(3) "foo"
}
jablko@tad:~/php5.2-200904292030$ 

Expected result:
----------------
array(2) {
  [0]=>
  string(3) "foo"
  [1]=>
  int(0)
}

Actual result:
--------------
array(1) {
  [0]=>
  string(3) "foo"
}