Comment 13 for bug 1552539

I think the cleanest way would be for "erase disk" to make sure that all partitions get unmounted/swapoff'ed before erasing.

Otherwise, it's fairly easy to disable systemd-gpt-auto-generator (the thing which discovers and enables GPT partitions of type swap) in casper (essentially just rm /root/lib/systemd/system-generators/systemd-gpt-auto-generator). That will work for this particular case, but of course still not be sufficient if the user mounts anything in the life session and then starts ubiquity to reformat.