Whats wrong with binery heap or i am not understand something?

[AlexM via Digitalmars-d-learn]

Please explain me whats wrong with binery heap?!!!

Simple example:

import std.container.binaryheap;
import std.stdio;

void main()
{
    int[] a = [ 4, 1, 3, 2, 16, 9, 10, 14, 8, 7 ];
    int[] b = new int[a.length];
    auto h = BinaryHeap!(int[], "a > b")(b, 0);
    foreach (e; a)
    {
        h.insert(e);
    }
    writeln(b); // [1, 2, 3, 4, 7, 9, 10, 14, 8, 16]
    writeln(h); // [1, 2, 3, 4, 7, 8, 9, 10, 14, 16]
    writeln(h.length); // 0 ???????
    h.insert(21);
    writeln(h); // [21] ????????
    writeln(h.length); // 0 ???????
}