Comment # 14 on bug 895447 from Dominique Leuenberger

(In reply to Marius Tomaschewski from comment #10)
> The only possibility to workaround it in yast2-network I currently see,
> would be to implement the "switch away from NM" like this -- and also
> to document in the release notes (for users doing it manually):
> 
>   # bnc#895447: NetworkManager does not cleanup on stop
>   # Ensure it is gone along with conflicting dhclients,
>   # ... before we switch over to another network.service.
>   systemctl --kill-who=all kill NetworkManager.service
>   systemctl stop NetworkManager.service
>   systemctl disable NetworkManager.service
> 
> Is this the way preferred by the NetworkManager?

Yes - the switching between Network services is a special thing and deserves
special handling, without breaking more normal use cases.