pantasks segfaults when you add a host that is down

[jhoblitt]

I imagine that same thing would happen if you added a host that doesn't exist.

controller is not responding (0 tries)
controller is not responding (1 tries)
Segmentation fault (core dumped)

[giebink]

Adding a host that doesn't exist during a simtest does not appear to cause a seg fault:
pantasks: controller host add ipp003
HostID: 2
pantasks: controller host check ipp003
host ipp003 is DOWN
pantasks: status

Scheduler is running
Controller is running