Example from d-idioms is incorrect

[TheGag96 via Digitalmars-d-learn]

I was looking at the d-idioms website today and saw this code 
example:

http://p0nce.github.io/d-idioms/#Adding-or-removing-an-element-from-arrays
And I was kind of irked. I just recently working with removing an 
element from an array in a small project I worked on two weeks 
ago, and I had to learn the hard way that to properly remove an 
element from an array in the way this example describes, you have 
to do array.length--; as well.

This code:

import std.stdio, std.algorithm;

void main() {
  int[] arr;  //ensuring it's dynamic
  arr ~= 1;
  arr ~= 5;
  arr ~= 10;
  arr.remove(1);
  writeln(arr);
  writeln(arr == [1, 10]);
  arr.length--;
  writeln(arr);
  writeln(arr == [1, 10]);
}

produces this output:

[1, 10, 10]
false
[1, 10]
true

Compiled and ran on Windows, dmd v2.067.0. Unless I'm totally 
missing something here, that website is giving some pretty wrong 
information... Was the behavior of the remove() function changed 
recently? Thanks guys.