Comment 11 for bug 1817655

Verification-done for cosmic:

With the changes and NetworkManager connection files now having a .nmconnection, the network still comes up and the system is still reachable, with the renderer value in netplan yaml changed to 'NetworkManager'.

ubuntu@civil-eft:~$ dpkg -l netplan.io | grep ii
ii netplan.io 0.96-0ubuntu0.18.10.2 amd64 YAML network configuration abstraction for various backends
ubuntu@civil-eft:~$ networkctl
IDX LINK TYPE OPERATIONAL SETUP
  1 lo loopback carrier unmanaged
  2 ens4 ether routable unmanaged

2 links listed.
ubuntu@civil-eft:~$ nmcli | cat
ens4: connected to netplan-ens4
 "Red Hat Virtio"
 ethernet (virtio_net), 52:54:00:02:E0:E0, hw, mtu 1500
 ip4 default, ip6 default
 inet4 10.3.21.28/20
 route4 10.3.16.0/20
 route4 0.0.0.0/0
 inet6 2001:470:b171::4/48
 inet6 fe80::5054:ff:fe02:e0e0/64
 route6 2001:470:b171::/48
 route6 ff00::/8
 route6 fe80::/64
 route6 ::/0

lo: unmanaged
 "lo"
 loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536

DNS configuration:
 servers: 149.56.20.136
 domains: cloud.cyphermox.net
 interface: ens4

 servers: 2001:470:b171::1
 domains: cloud.cyphermox.net
 interface: ens4

Use "nmcli device show" to get complete information about known devices and
"nmcli connection show" to get an overview on active connection profiles.

Consult nmcli(1) and nmcli-examples(5) manual pages for complete usage details.
ubuntu@civil-eft:~$ sudo ls -l /run/NetworkManager/system-connections/
total 4
-rw------- 1 root root 360 Apr 2 16:18 netplan-ens4.nmconnection
ubuntu@civil-eft:~$