MAC spoofing failure sometimes does not disable networking
In some of our most constrived test suite scenarios ("MAC address spoofing fails and macchanger returns true" and "MAC address spoofing fails and the module is not removed") I've recently seen failures: the network interface or NetworkManager is left enabled.
I've seen this happen with both systemd v240 and v241, and both Linux 4.19.20 and 4.19.28.
In passing, I wonder if we should give
MACAddressPolicy= a try (
systemd.link(5)), let udev set a random MAC address, and keep only our code that detects whether the MAC address was successfully spoofed and if not, switches to "panic mode".