May be we juste have to wait that these packages are updated to 0.6.0-1~bpo8+1 as well.
-- Regards, Nicolas KAROLAK
Upgrade from python-acme_0.5.0-1~bpo8+1 to python-acme_0.6.0-1~bpo8+1
ask for removing letsencrypt and python-letsencrypt.
