Static IP addresses fail!

[compdoc]

>This is the file that udev uses to map physical interfaces to their
>ethX names. It doesn't need 'cleaning' when you make configuration
>changes to the cards

You're wrong. After adding and removing physical network cards, this file
can come to contain incorrect entries.

It can need 'cleaning', and I've had to do it a few times. Whatever code
that maintains this file is not very robust, and it can add several entries
for the same card, or screw up the entries.