nodesensors and nodeconfig printed an error and exited 0, so
`nodesensors n1 && next-step` ran next-step after the read it guarded had
already failed.
nodesensors had three of these: the per-node branch never set the exit code,
the top-level branch beside it read `exitcode |= exitcode`, and a normal
return from main() fell off the end of the file. nodeconfig accumulates with
|= all through its read path except the last line, which assigned, so a
failed bmc configuration read was discarded by the system read after it.
The fixed branches now match how nodehealth and client.py spell the same
thing.
Markus Hilger
5d7fadf615