Sometimes invoker returns OK result when there was a failure

[p4vook]

When minion::spawn returns an error, invoker returns OK with spawn_error set to true. However, sometimes this indicates that sandbox failed before even starting a command. This should be considered as a failure.

[MikailBag]

Launch failure can have legitimate reasons. E.g. some compilers can produce invalid binary given invalid programs.

Currently. I don't see good criteria for distinction "a launch error caused by an error in the program | a launch error caused by an error in the invoke request | a launch error caused by a bug in the invoker".