Time\Duration::__unserialize() accepts a "negative zero" payload. #24505

<?php

$payload = 'O:13:"Time\Duration":3:{s:7:"seconds";i:0;s:11:"nanoseconds";i:0;s:8:"negative";b:1;}';
$d = unserialize($payload);

var_dump($d->negative); // expected: exception, or false. actual: true
var_dump(Time\Duration::compare($d, Time\Duration::fromSeconds(0))); // int(0)
var_dump($d->absolute()->negative); // actual: true (absolute() of a value is still "negative")
echo json_encode($d), "\n"; // actual: {"seconds":0,"nanoseconds":0,"negative":true}
echo serialize(Time\Duration::fromSeconds(0)->negate()), "\n"; // canonical zero: ...s:8:"negative";b:0;}

// For comparison, other non-canonical payloads are rejected:
try {
    unserialize('O:13:"Time\Duration":3:{s:7:"seconds";i:-1;s:11:"nanoseconds";i:0;s:8:"negative";b:0;}');
} catch (Exception $e) {
    echo get_class($e), ': ', $e->getMessage(), "\n";
}