Description:
------------
$php -v

```
PHP 7.2.4-1+ubuntu16.04.1+deb.sury.org+1 (cli) (built: Apr  5 2018 08:53:57) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.2.4-1+ubuntu16.04.1+deb.sury.org+1, Copyright (c) 1999-2018, by Zend Technologies
    with Xdebug v2.6.0, Copyright (c) 2002-2018, by Derick Rethans
```

I have a base class and derived class with same member name.
In the base class if member is protected it breaks the serialize/unserialize.
However, if the member is private functionality works as expected. 

This works on:
PHP 7.1.11-1+ubuntu16.04.1+deb.sury.org+1 (cli) (built: Oct 27 2017 13:49:56) ( NTS )

Test script:
---------------
<?php
class Base {
	private $id;
	public function __construct($id)
	{
		$this->id = $id;
	}
}
class Derived extends Base {
	protected $id;
	public function __construct($id)
	{
		parent::__construct($id + 20);
		$this->id = $id;
	}
}
$a = new Derived(44);
$s = serialize($a);
$u = unserialize($s);
print_r($u);

Expected result:
----------------
Derived Object
(
    [id:protected] => 44
    [id:Base:private] => 64
)


Actual result:
--------------
Derived Object
(
    [id:protected] => 64
    [id:Base:private] => 
)