Description:
------------


PHP 7.1.6-1~ubuntu16.04.1+deb.sury.org+1 (cli) (built: Jun  9 2017 08:26:34) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2017 Zend Technologies
    with Zend OPcache v7.1.6-1~ubuntu16.04.1+deb.sury.org+1, Copyright (c) 1999-2017, by Zend Technologies
    with Xdebug v2.5.5, Copyright (c) 2002-2017, by Derick Rethans

Test script:
---------------
class Foobar implements \Serializable
{
    /** @return string */
    public function serialize(): string
    {
        return serialize(new \DateTimeZone('Europe/Andorra'));
    }

    /** @param string $serialized */
    public function unserialize($serialized)
    {
        var_dump($serialized);
        var_dump(unserialize($serialized)->getName());
    }
}

(new Foobar())->unserialize((new Foobar())->serialize());
var_dump(unserialize(serialize(new Foobar())));

Expected result:
----------------
The DateTimeZone object correct initialization

Actual result:
--------------
/tmp/test.php:14:
string(86) "O:12:"DateTimeZone":2:{s:13:"timezone_type";i:3;s:8:"timezone";s:14:"Europe/Andorra";}"
/tmp/test.php:15:
string(14) "Europe/Andorra"
/tmp/test.php:14:
string(86) "O:12:"DateTimeZone":2:{s:13:"timezone_type";i:3;s:8:"timezone";s:14:"Europe/Andorra";}"
PHP Warning:  DateTimeZone::getName(): The DateTimeZone object has not been correctly initialized by its constructor in /tmp/test.php on line 15
PHP Stack trace:
PHP   1. {main}() /tmp/test.php:0
PHP   2. unserialize() /tmp/test.php:20
PHP   3. Foobar->unserialize() /tmp/test.php:20
PHP   4. DateTimeZone->getName() /tmp/test.php:15
/tmp/test.php:15:
bool(false)
/tmp/test.php:20:
class Foobar#1 (0) {
}