Disabling IPv4 autoconf does not clean up 169.254/16 address on interface

[troglobit]

Current Behavior

While adding support for #628, the corresponding test was extended with a final pass which disables IPv4 autoconf to verify any 169.254/16 is removed.

Turns out this does not work, at all.

Expected Behavior

When disabling avahi-autoipd on an interface, it should clean up after itself as a final step.

Steps To Reproduce

.

Additional information

Inspecting the code it became evident that upon receiving SIGTERM, the daemon sends an internal message to call out to the /etc/avahi/avahi-autoipd.action script. However, immediately after sending that message the process closes all its open sockets and exits.

With a process monitor like Finit, the PID is collected and the entire remaining process group is reaped, leading the lingering dispatcher process to be stopped, sometimes even before having launched the script.