Description:
------------
The documentation says references and circular references should serialize 
properly. I've found that serialize would first copy the referenced variable, 
before detecting the reference.

This not only doubles the serialized output, but produced incorrect copy when 
unserialized.

Test script:
---------------
$original = array('hello');
$original[] = & $original;

echo serialize($original);
// Output (notice the duplication):
// "a:2:{i:0;s:5:"hello";i:1;a:2:{i:0;s:5:"hello";i:1;R:3;}}"

$duplicate = unserialize(serialize($x));

// Now I modify both the original and the duplicate in an identical way.
// But I get different results, because the duplicate points to a copy of
// itself, instead of pointing to itself.

$original[0] = 'world';
$duplicate[0] = 'world';

var_dump($original);
// Produces (notice it says "world" both times, i.e. it points to itself):
// array(2) { [0]=> string(5) "world" [1]=> &array(2) { [0]=> string(5) "world" [1]=> *RECURSION* } } 

var_dump($duplicate);
// Produces (notice the second time it says "hello" i.e. it's a copy):
// array(2) { [0]=> string(5) "world" [1]=> &array(2) { [0]=> string(5) "hello" [1]=> *RECURSION* } }

Expected result:
----------------
There should be NO copies of "hello" left:

array(2) { [0]=> string(5) "world" [1]=> &array(2) { [0]=> string(5) "world" [1]=> 
*RECURSION* } }

There should be NO duplication in the serialized output:

"a:2:{i:0;s:5:"hello";i:1;???;}" (Fill-in the "???" appropriately :) )

Actual result:
--------------
A copy of "hello" is left:

array(2) { [0]=> string(5) "world" [1]=> &array(2) { [0]=> string(5) "hello" [1]=> 
*RECURSION* } }

There is duplication in the serialized output:

"a:2:{i:0;s:5:"hello";i:1;a:2:{i:0;s:5:"hello";i:1;R:3;}}"