Comment 33 for bug 1770082

I'm not completely sure where the code lives in cloud-init; it looks a bit like what's in:

cloudinit/net/netplan.py

But the code does read as though it should not be running 'udevadm test-builtin net_setup_link'. However, deploying a system with MAAS shows a /etc/cloud/cloud.cfg.d/50-curtin-networking.cfg file, which contains data referring to the network interfaces:

network:
  config:
  - id: ens6
    mac_address: 52:54:00:31:27:2c
    mtu: 1500
    name: ens6
    subnets:
    - address: 10.3.99.13/24
      gateway: 10.3.99.1
      type: static
    type: physical
  version: 1

With that file in place, any netplan config renaming the interface to something other than ens6 will see the interface being renamed *again* back to ens6, when that file is removed, this behavior does not appear.