Make sure sshd.pid file survives running "prepare".
Make sure sshd.pid file survives running "prepare".

If we don't, then you cannot HUP sshd to have it re-read the config file.
Apparently this didn't used to matter, but now if we do not HUP sshd,
the initial V1 key-pair does not work.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome