How on earth did this bug make it into PHP 5.1.3?

Expected result:----------------Array(    [masivasid] => Array        (            [id_1] => Nzzz1            [id_2] => Nzzz2        )

)

Actual result:--------------Array(    [masivasid] => Array        (            [id_1] => Nzzz1            [id_2] => Array                (                    [id_1] => Nzzz2                )

        )

)

This should have broken more or less every single web application out there which uses forms.

Don't upgrade to 5.1.3; instead wait for 5.1.4.