Uploads before 2009/8/28 with a `?` in the filename will 404

[precipice]

It is likely that uploads before 2009/8/28 or so which have a ? in the filename will fail to export and report a 404 error instead. This is due to a problem with S3 filenames.

The script should let people know if they are hitting this bug and should direct them to write [email protected] if they want help getting those files back.