Clean up the exit codes; use die consistently so that we return -1 on fatal errors, and error codes >= 1 for assign errors. The batch system depends on these error codes to determine if a batch needs to be punted from the system.
Clean up the exit codes; use die consistently so that we return -1
on fatal errors, and error codes >= 1 for assign errors. The batch
system depends on these error codes to determine if a batch needs
to be punted from the system.

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