Comment 8 for bug 1819014

Verification done for bionic on a Raspberry Pi Compute Module 3 with USB wifi adapter:

ubuntu@ubuntu:~$ dpkg -l netplan.io | grep ^ii
ii netplan.io 0.96-0ubuntu0.18.04.2 arm64 YAML network configuration abstraction for various backends
ubuntu@ubuntu:~$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 80:1f:02:e6:92:c1 brd ff:ff:ff:ff:ff:ff
    inet 192.168.80.83/16 brd 192.168.255.255 scope global dynamic wlan0
       valid_lft 42998sec preferred_lft 42998sec
    inet6 fd13:37d0:1c6d::b1c/128 scope global noprefixroute
       valid_lft forever preferred_lft forever
    inet6 fd13:37d0:1c6d:0:821f:2ff:fee6:92c1/64 scope global mngtmpaddr noprefixroute
       valid_lft forever preferred_lft forever
    inet6 fe80::821f:2ff:fee6:92c1/64 scope link
       valid_lft forever preferred_lft forever
ubuntu@ubuntu:~$ cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by
# the datasource. Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    version: 2
    renderer: networkd
    wifis:
        wlan0:
            dhcp4: true
            access-points:
                "waveform":
                    password: <redacted>
ubuntu@ubuntu:~$ systemd-analyze blame | grep wait-online
           942ms systemd-networkd-wait-online.service

Previously, systemd-networkd-wait-online had been 2m 17sec. After upgrade of netplan.io, reboot time was considerably shorter.