Text format cacheability is not updated

Another, related issue from: http://drupal.org/node/836000

if you do this:

$formats = filter_formats();
foreach ($formats as $format) {
  filter_format_save($format);
}

All your filters will be re-saved with status = 0 and their settings completely wiped out.

I had to do this to get the formats to resave properly, which is ugly as hell:

  $formats = filter_formats();
  foreach ($formats as $format) {
    $format->filters = filter_list_format($format->format);
    // filter_format_save() expects filters to be an array, however
    // filter_list_format() gives us objects.
    foreach ($format->filters as $key => $value) {
      $format->filters[$key] = (array) $value;
    }
    filter_format_save($format);
  }

It took a fair bit of debugging to figure out why all my text formats suddenly stopped working. That's probably one for Drupal 8, but it ought to be possible to load and save a format without having to call extra functions to avoid losing data, or at least we should document this very clearly at the top of filter_format_save()