To avoid this issue for now I defined eth0 as wanted in /etc/network/interfaces and have "managed=false" in /etc/NetworkManager/NetworkManager.conf See [1]
[1] https://wiki.debian.org/NetworkManager#Wired_Networks_are_Unmanaged -- To UNSUBSCRIBE, email to debian-bugs-rc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org