Admin cannot create versions on nodes for which he is the lockowner

public void testCheckInCheckoutLocked() throws Exception {

        n1.addMixin(mixLockable);
        n1.getSession().save();

        Session adminSession = getHelper().getSuperuserSession();
        Node n = adminSession.getNode(n1.getPath());
        n.lock(true, false);
        n.getSession().save();
        adminSession.logout();

        adminSession = getHelper().getSuperuserSession();
        Node na = adminSession.getNode(n1.getPath());
        na.checkin();
        na.checkout();
    }