Change in GRES behavior for job steps: A job step's default generic
    resource allocation will be set to that of the job. If a job step's --gres
    value is set to "none" then none of the generic resources which have been
    allocated to the job will be allocated to the job step.
Add srun environment value of SLURM_STEP_GRES to set default --gres value
    for a job step.