i managed to break https://github.com/pantsbuild/pants/pull/6388 even more so now i can get at least the error message to reproduce in ci -- it's still not clear whether this is like a breakage i created that is unrelated -- i'm choosing to view it as potentially a clue https://travis-ci.org/pantsbuild/pants/jobs/428897275. i can reliably repro this and other shutdowns locally too (shutdowns just in this branch, not referring to any other shutdowns)