Created attachment 211526 [details]
Attached patch adds B2 option (enabled by default same as the other backends).
Tested and working with Python 3.7 on FreeBSD 12.1-RELEASE.
I'll test and commit in a few days.
A commit references this bug:
Date: Thu Feb 13 23:02:52 UTC 2020
New revision: 526073
sysutils/duplicity-devel: Add Backblaze B2 support
Submitted by: PopularMoment@protonmail.com