fix another subtle state race
pilot.{stdout,stderr,logfile} are not available.

also added some more state transition safeties

;
snapshot
fix wait for pilot cancellation
Merge branch 'devel' into feature/shutdown
clean pilot state
snasphot
snapshot
add another backfilling example
use unit restart in example
Merge branch 'devel' into feature/unit_restart
merge from devel
Merge branch 'devel' into feature/shutdown
merge from devel
Merge branch 'devel' into feature/shutdown
merge from devel
merge from devel
Merge branch 'devel' into feature/pilot_error
merge from devel
Merge branch 'devel' into feature/unit_restart