IllegalStateException с каскадированием Hibernate 4 и ManyToOne

У меня есть эти два класса

MyItem Object:

@Entity
public class MyItem implements Serializable {

    @Id
    private Integer id;
    @ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE})
    private Component defaultComponent;
    @ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE})
    private Component masterComponent;

    //default constructor, getter, setter, equals and hashCode
}

Component Object:

@Entity
public class Component implements Serializable {

    @Id
    private String name;

    //again, default constructor, getter, setter, equals and hashCode
}

И я пытаюсь сохранить те со следующим кодом:

public class Test {

    public static void main(String[] args) {
        Component c1 = new Component();
        c1.setName("comp");
        Component c2 = new Component();
        c2.setName("comp");
        System.out.println(c1.equals(c2)); //TRUE

        MyItem item = new MyItem();
        item.setId(5);
        item.setDefaultComponent(c1);
        item.setMasterComponent(c2);

        ItemDAO itemDAO = new ItemDAO();
        itemDAO.merge(item);
    }
}

В то время как это прекрасно работает с Hibernate 3.6, Hibernate 4.1.3 выдает

Exception in thread "main" java.lang.IllegalStateException: An entity copy was already assigned to a different entity.
        at org.hibernate.event.internal.EventCache.put(EventCache.java:184)
        at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:285)
        at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
        at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:914)
        at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:896)
        at org.hibernate.engine.spi.CascadingAction$6.cascade(CascadingAction.java:288)
        at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:380)
        at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:323)
        at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
        at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:165)
        at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:423)
        at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:213)
        at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:282)
        at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
        at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:76)
        at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:904)
        at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:888)
        at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:892)
        at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:874)
        at sandbox.h4bug.Test$GenericDAO.merge(Test.java:79)
        at sandbox.h4bug.Test.main(Test.java:25)

Бэкэнд базы данных - h2 (но то же самое происходит с hsqldb или derby). Что я делаю неправильно?