Absolute URL for index.php in editor_plugin.js

I noticed that in the editor_plugin.js file, the index.php reference is absolute, i.e.:
template['file'] = '/index.php?q=am/load/tinymce';

That means that if your installation of Drupal is anywhere other than the website root, it's going to break. My test installation is in /drupal, for example, so there's no /index.php.

I got around it by just removing the trailing / on the URL to make it relative and now the AM seems to work a treat.