Not sure if this is a bug but serialize() cannot work with arrays that holds elements which points to the array itself

<?php
        $b=array(1,2,4);
  $b[]=&$b;
        $str=serialize($b);
        var_dump($b);
        var_dump($str);
        $c=unserialize($str);
        var_dump($c);
?>
The ouput is:
array(4) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(4)
  [3]=>
  *RECURSION*
}
string(64) "a:4:{i:0;i:1;i:1;i:2;i:2;i:4;i:3;a:4:{i:0;i:1;i:1;i:2;i:2;i:4;}}"
bool(false)

If 
$b[]=&$b;
removed the output is:
array(3) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(4)
}
string(30) "a:3:{i:0;i:1;i:1;i:2;i:2;i:4;}"
array(3) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(4)
}
That's ok.
Serialize() have either to check against recursion or encode somehow the recursion in the serialized(great BC impact).