to pass the memory check cleanly.

BLUEGENE - env vars such as SLURM_NNODES, SLURM_JOB_NUM_NODES, and SLURM_JOB_CPUS_PER_NODE now reference cnode counts instead of midplane counts.  SLURM_NODELIST still references midplane names.

error instead of doing an assertion failure.

move some duplicated logic into a common function