cache.inc cannot always write commandfiles since the parent folder is missing

I had an issue on my Windows workstation with Drupal 7.15 and Drush 5.2 or 5.7 when clearing the cache for all 17 sites at the same time. But I think this also occurred on my Linux production server, but cannot check that right now.

When trying to clear the cache using drush @sites cache-clear all, the folder C:\Users\USERNAME/.drush/cache/default/ keeps being created and removed, since I see it flashing by in explorer.

Sometimes the result was (say in 50% of the cases):

'all' cache was cleared in C:/drupal#SITENAME

but sometimes it was:

file_put_contents(C:\Users\USERNAME/.drush/cache/default/5.7-commandfiles-5-360407b77294ab6be6b70c5e54073079.cache): failed to open stream: No such file or directory cache.inc:433 [warning]

Drush seemed to have problems with the writing of a file, so I wrote the following directory check for function DrushJSONCache::writeFile(), situated in cache.inc, and it worked.

/**
 * JSON cache storage backend.
 */
class DrushJSONCache extends DrushFileCache {
  const EXTENSION = '.json';

  function readFile($filename) {
    $item = file_get_contents($filename);
    return $item ? (object)drush_json_decode($item) : FALSE;
  }

  function writeFile($filename, $cache) {
    $dirname = dirname($filename); // <- added line
    if (!is_dir($dirname)) mkdir($dirname, 0777, true); // <- added line
  
    return file_put_contents($filename, drush_json_encode($cache));
  }
}