Why doesn't CasperJS see the changes made by Brython?

casper_brython.js

var utils = require('utils');
var casper = require('casper').create();

casper.start('http://profgra.org/lycee/squelettes/html_css_js1.html', function() {
    // was 'avant', JS put 'apres' instead
    utils.dump(this.getElementsInfo('#ici')[0].html);
    this.captureSelector('apres.png', 'body');
});

casper.thenOpen('http://brython.info/', function() {
    // was empty, brython should have filled it
    var please_wait = 10000;
    this.wait(please_wait, function() {
        this.echo("I've waited " + please_wait);
        utils.dump(this.getElementsInfo('#content')[0].html);
        utils.dump(this.getElementsInfo('#content'));
        this.captureSelector('content.png', 'body');
    });
});

casper.options.waitTimeout = 60000;
casper.waitForSelectorTextChange('#content', function() {
    utils.dump(this.getElementsInfo('#content')[0].html);
    utils.dump(this.getElementsInfo('#content'));
    this.captureSelector('contentwait.png', 'body');
});

casper.run();