Description:
------------
Memcache->set($key, $value) changes $value and passes it back from the wrapping function

Reproduce code:
---------------
$m = new Memcache();
$m->addServer('127.0.0.1', 11211);

function s($k, $v)
{
        global $m;

        var_dump($v);
        $m->set($k, $v);
        var_dump($v);
}

$x = FALSE;
var_dump($x);
s('x', $x);
var_dump($x);

Expected result:
----------------
bool(false)
bool(false)
bool(false)
bool(false)


Actual result:
--------------
bool(false)
bool(false)
string(0) ""
string(0) ""