Comment 2 for bug 1840044

Perhaps of interest, I started a boto3 back-end. It's rough, not tested under hard conditions, and lack feature parity, but it's a start. See my branch: https://code.launchpad.net/~carlalex/duplicity/duplicity

A quick test does seem to indicate that it addresses my problem with buckets with governance policies (which I want to use as a backstop to protect backups against ransomware)