Error: write EPIPE node8

Question

This is https://github.com/mapbox/ecs-watchbot/pull/205/files#diff-644d8ede25bb88427ccf4229d03bba1bR19 breaking the test with

[worker] waitFor, exit 0
events.js:183
  throw er; // Unhandled 'error' event
  ^
Error: write EPIPE
at _errnoException (util.js:992:11)
at WriteWrap.afterWrite [as oncomplete] (net.js:864:14)

Here, when run locally npm run test this fails.