firewalld: Does not get setup during first boot

Currently, when a new FreedomBox image is booted, it's web interface is not available over the network. If we wait for a few minutes (for the first setup to complete) and then reboot, everything works as expected.

This is due to firewalld failing to flush existing rules. The following message can be seen the system log.

line 4: RULE_REPLACE failed (No such file or directory): rule in chain INPUT
line 4: RULE_REPLACE failed (No such file or directory): rule in chain

This is a bug in firewalld/iptables-restore. It is being tracked here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=914694