Download link not relative to Drupal root

I have a Drupal installation sandbox, but not on its own domain (http://sandbox.com/drupal/). When I make a backup I get the normal message list:

• Database backed up successfully.
• Files backed up successfully.
• Click this filename to download: drupal-backup-20070426035619-842029818.tar.gz

However, the link does not point to the file. The path should be (if no directory is given):

http://sandbox.com/drupal/drupal-backup-20070426035619-842029818.tar.gz

But I get this instead:

http://sandbox.com/drupal-backup-20070426035619-842029818.tar.gz

It shows up on the list of backups fine. I tracked this down to line 205 of backup.module.

204  $message = t("Click this filename to download: ")
205  		. "<a href=\"/". $backup_file . "\">" . $backup_file . "</a>";
206  	watchdog("backup", $message);
207  	drupal_set_message($message);

I put in the path of my installation and it worked fine:

205  		. "<a href=\"/drupal/". $backup_file . "\">" . $backup_file . "</a>";

Again, this is only for the initial message with the link. The list of files below it all have the correct paths. Also, I tested it with a directory chosen for the backup location with the same results.

It really pains me to bring this up, but honestly I know jack about PHP, and I don't know how to put the directory in. I looked at the array you use in forms.inc.php, but I don't know how to pop that in the module.

It isn't a large problem, but since you are making it for non-techies, and someone may put up an installation that is not at the root with the domain, it is worth figuring out.

Thanks for the great module, and I hope I learn something from this.

maiki