ufw status fails due to xtables lock

[Rowan Wookey]

I have a process which runs ufw status regularly to check the firewall is running. I also have docker containers being spun up and down on a regular basis for CI/CD when the docker containers are spawning if ufw status is run it sometimes fails with the error:

status failed (1) -- ERROR: problem running iptables: Another app is currently holding the xtables lock. Perhaps you want to use the -w option?

The attached patch adds the -w flag so iptables waits until the lock is released to execute.