During backporting test fixes was found product issue which was hidden by test error.
Method remove() from ArrayBlockingQueue's iterator work incorrectly
if delete no first element. For example:

import java.util.Iterator;
import java.util.concurrent.ArrayBlockingQueue;

public class ABQueue {

    public static void main(String[] args) throws Exception {
        ArrayBlockingQueue<Integer> queue = new ArrayBlockingQueue<Integer>(3);
        queue.add(1);
        queue.add(2);
        queue.add(3);
        System.out.println("Size before: "+queue.size());
        Iterator<Integer> i = queue.iterator();
        i.next();
        i.next();
        i.remove();
        i.next();
        i.remove();
        System.out.println("Size after: "+queue.size());
    }
}

Results for 1.6.0_29b11:
java.exe ABQueue
Size before: 3
Size after: 1

Results for 1.6.0_30b12:
java.exe ABQueue
Size before: 3
Size after: 2