libarchive apparently cannot be used for in-place modification of (e.g. adding files to) existing archives, so if a bundle already exists, this code would over-write it with a new archive containing just the latest packet. Issue reported by acn (IMZADI) via DOVE-Net.

I could and might create an update_archive() function which extracts and re-creates an archive with additional files, but since I don't have that yet, just disable this for now and always use an external archive utility to create or update bundles (so again, an "Archive" configuration is required in your sbbsecho.ini file, which you most likely already have).