ERROR: extending oxbasket 4.7

//metadata.php:
//-----------------------------------------------------
$sMetadataVersion = ‘1.1’;
$aModule = array(
‘extend’ => array(
“oxbasket” => “ddfreeshipping/models/oxddbasket”
),
<…>some other tpls, blocks and etc<…>
);

//modules/ddfreeshipping/models/oxddbasket/oxddbasket.php:
//-----------------------------------------------------
class oxDdbasket extends oxDdbasket_parent {}
// nothing more in this file.
//------------------------------------------------------------------------------------------------------------------

When I activate module and and try to load http://oxid.dev/index.php?cl=payment
(2 products are in the basket)

I get an error:
Fatal error: Call to a member function getBruttoPrice() on a non-object in C:\wamp\www\oxid\core\oxpricelist.php on line 59

everything works if I disable the module.

in oxpricelist.php function getBruttoSum() I wrote a line:
var_dump($this->_aList);
and while my module is active I get this dump before error:

array (size=2)
0 =>
array (size=0)
empty
1 => string ‘http://oxid.dev/out/pictures/generated/product/1/87_87_75/ion_sol_kite_waist_2011_1.jpg’ (length=87)

I use default test data. I cant understand why the string is there?
If I disable my module, the dump is protty normal: its an array that contains oxprice objects.

I use 4.7 OXID.

please help…

edited:
seems the bug apairs only with PHP v5.4 :confused:
https://bugs.php.net/bug.php?id=55801