PoC for error when assigning arrays with references to the PHP LUA extension

$ cat /etc/issue
Ubuntu 16.04.1 LTS \n \l

$ php -v
PHP 7.0.13-0ubuntu0.16.04.1 (cli) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.13-0ubuntu0.16.04.1, Copyright (c) 1999-2016, by Zend Technologies

$ dpkg -s liblua5.2-dev | grep Version
Version: 5.2.4-1ubuntu1

$ php -i | grep '^lua '
lua support => enabled
lua extension version => 2.0.2
lua release => Lua 5.2.4
lua copyright => Lua 5.2.4  Copyright (C) 1994-2015 Lua.org, PUC-Rio
lua authors => R. Ierusalimschy, L. H. de Figueiredo, W. Celes

$ php test-assign.php
Plain array:
array(1) {
  ["a"]=>
  string(1) "b"
}
Referenced array:
array(1) {
  ["a"]=>
  &string(1) "b"
}
Arrays are identical

Assigning plain array...
Plain array assigned.

Assigning referenced array...
PHP Fatal error:  Lua::assign(): unsupported type `string' for lua in /home/roel/git/php-lua-reference-error/test-assign.php on line 25