orm: Cascade deletion complicate-referenced entities does not work [ForeignKeyConstraintViolationException]

[Doctrine\DBAL\Exception\ForeignKeyConstraintViolationException]             
  An exception occurred while executing 'DELETE FROM subitem WHERE id = ?' wi  
  th params [4]:                                                               
  SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or upda  
  te a parent row: a foreign key constraint fails (`shop`.`item`, CONSTRAINT   
  `FK_1F1B251EB3AE4213` FOREIGN KEY (`featured_item_id`) REFERENCES `subitem`  
   (`id`))                                                                     

is caused by

        $item = new Item();
        $sub1 = new Subitem();
        $sub2 = new Subitem();
        $item->addItem($sub1);
        $item->addItem($sub2);
        $item->setFeaturedItem($sub2);
        $em->persist($item);
        $em->flush();
        $em->remove($item);
        $em->flush();

Entity mappings:

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity
 */
class Item
{

    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @var ArrayCollection
     *
     * @ORM\OneToMany(targetEntity="Subitem", mappedBy="item", cascade={"all"}, orphanRemoval=true)
     */
    protected $items;

    /**
     * @var Subitem
     *
     * @ORM\ManyToOne(targetEntity="Subitem")
     */
    protected $featuredItem;

    public function __construct()
    {
        $this->items = new ArrayCollection();
    }

    /**
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * @return ArrayCollection
     */
    public function getItems()
    {
        return $this->items;
    }

    public function addItem(Subitem $item)
    {
        $this->items[] = $item;
        $item->setItem($this);
    }

    public function removeItem(Subitem $item  = null) {
        if ($this->featuredItem === $item) {
            $this->featuredItem = null;
        }
        $this->items->removeElement($item);
    }

    /**
     * @return Subitem
     */
    public function getFeaturedItem()
    {
        return $this->featuredItem;
    }

    /**
     * @param Subitem $featuredItem
     */
    public function setFeaturedItem(Subitem $featuredItem)
    {
        $this->featuredItem = $featuredItem;
    }

}

/**
 * @ORM\Entity
 */
class Subitem
{

    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @var Item
     *
     * @ORM\ManyToOne(targetEntity="Item", inversedBy="items")
     */
    protected $item;

    /**
     * @return integer
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * @return Item
     */
    public function getItem()
    {
        return $this->item;
    }

    /**
     * @param Item $item
     */
    public function setItem($item)
    {
        $this->item = $item;
    }

}