Update 4.1 -> 4.2 bricht ab. System in undefiniertem Zustand

Docker CE (Community Edition) does not support btrfs at all anymore.
Docker ER (Enterprise Edition) support btrfs only on SLES.

Docker doc: https://docs.docker.com/engine/userguide/storagedriver/selectadriver/#docker-ee-and-cs-engine
Compatibility Matrix: https://success.docker.com/Policies/Compatibility_Matrix