Comment 8 for bug 1735160

pymacaroons does have one potentially-interesting backward-incompatible change, which is that Caveat.caveat_id and Macaroon.identifier are now bytes rather than str. I think the only place this is at all likely to cause a problem in xenial is in snapcraft, and it's definitely worth checking whether "snapcraft login" still works.

The py-macaroon-bakery change looks OK-ish, as long as (obviously) somebody confirms that it's wire-compatible with the servers this is intended to talk to.