free memory if mid-return
When no more job IDs available, return EAGAIN error to user

The job submit commands will retry.
Previously the slurmctld daemon generated a fatal error
Explain sched/builtin plugin
Merge branch 'slurm-2.5'
Merge branch 'master' of https://github.com/SchedMD/slurm
Solving memory leak when job has a partition list