Add fix for multi-node race-on-shutdown.
Add fix for multi-node race-on-shutdown.

Hack, but sufficient for the time being to prevent Travis builds from
blowing up every other run.

ergl/lasp,lasp-lang/lasp,ergl/lasp,lasp-lang/lasp,ergl/lasp,lasp-lang/lasp,ergl/lasp,lasp-lang/lasp