investigate flaky known_issues/test-vm-timeout-escape-nexttick

https://ci.nodejs.org/job/node-test-commit-smartos/21423/nodes=smartos16-64/console

```console
21:00:05 not ok 2313 known_issues/test-vm-timeout-escape-nexttick
21:00:05   ---
21:00:05   duration_ms: 0.525
21:00:05   severity: fail
21:00:05   stack: |-
21:00:05   ...
```

@jasnell 