Instead of overriding process.returncode and utilizing that attribute to determine if the process has timed out, utilize a special _timed_out attribute instead.
Instead of overriding process.returncode and utilizing that attribute to
determine if the process has timed out, utilize a special _timed_out
attribute instead.

This way we don't interfere with upstream logic which may base decisions
based on the value of the process returncode value.

Plexxi/st2,StackStorm/st2,Plexxi/st2,StackStorm/st2,nzlosh/st2,Plexxi/st2,StackStorm/st2,Plexxi/st2,nzlosh/st2,nzlosh/st2,nzlosh/st2,StackStorm/st2