lpsetup probably shouldn't overwrite your SSH keys with nonsense

If you're stupid - like me - you can do something like this, misunderstanding what -v and -b do:

 ./lp-setup lxc-install [...] -v /home/graham/.ssh/id_rsa -b /home/graham/.ssh/id_rsa.pub.

What then happens is that both files get overwritten. id_rsa contains "/home/graham/.ssh/id_rsa" and .pub contains " /home/graham/.ssh/id_rsa.pub."

lp-setup probably shouldn't let you blow away your SSH keys through stupidity. Instead, it should abort if id_rsa and id_rsa.pub already exist.