Drupal - imagecache problems with special characters

If you upload an image with an ampersand (&) in the filename, imagecache will refuse to display the image.
After a bit of investigation I found that imagecache has a problem with a number of special characters in the image filenames.

The solution is a little imagecache theme override in the template.php
Just copy & paste this code to the end of your template.php in the theme folder.

function phptemplate_imagecache($presetname, $path, $alt = '', 
$title = '', $attributes = NULL, $getsize = TRUE) {
  // Check is_null() so people can intentionally pass an empty array of
  // to override the defaults completely.
  if (is_null($attributes)) {
    $attributes = array('class' => 'imagecache imagecache-'. $presetname);
  }
  if ($getsize && ($image = image_get_info(imagecache_create_path($presetname, $path)))) {
    $attributes['width'] = $image['width'];
    $attributes['height'] = $image['height'];
  }

  $attributes = drupal_attributes($attributes);
  // here we add drupal_urlencode to make sure the path is encoded.
  $imagecache_url = imagecache_create_url($presetname, drupal_urlencode($path));
  return '';
}