Comment 5 for bug 1761096

This is complicated indeed. I also spotted this in the logs during the long wait:
Oct 25 21:16:07 xenial-squid-dnsmasq systemd[1]: nss-lookup.target: Job nss-lookup.target/start failed with result 'dependency'.

and nss-lookup.target has something related to dnsmasq:
root@xenial-squid-dnsmasq:~# systemctl status nss-lookup.target
● nss-lookup.target - Host and Network Name Lookups
   Loaded: loaded (/etc/insserv.conf.d/dnsmasq; static; vendor preset: enabled)
  Drop-In: /run/systemd/generator/nss-lookup.target.d
           └─50-hard-dependency-dnsmasq-$named.conf
   Active: active since Thu 2018-10-25 21:19:41 UTC; 53s ago
     Docs: man:systemd.special(7)