Remote rebuilding requires root access, but I don't want root ssh
access (even by ssh key) to be a permanent fixture of my servers. So
I've changed 'hey push' to copy my remote user's `authorized_keys` to
/root/.ssh/ temporarily, until the rebuild is complete. It is removed
afterwards.
This should be done non-destructively in the future, but it suits my
needs for now.
e703bd374d