Investigate flaky test-fs-read-buffer-tostring-fail

[Trott]

Example failure:

• ubuntu1504-64

[Trott]

Stress test to see if it occurs with enough frequency such that a fix can be confirmed:

• https://ci.nodejs.org/job/node-stress-single-test/68/nodes=ubuntu1504-64/console

[jbergstroem]

• echo '1078 OK: 1078 NOT OK: 0'

perhaps related to tests run prior?

[Trott]

Looks awfully similar to #4046 just not as extreme. (Healthy server can take 10 seconds to run the test rather than 30, but still, 10 seconds is a lot and tie up some resources and you get a timeout.) Both tests are also related to toString() failures. Memory constraints, maybe? Anyway, since we've never seen it before, and the stress test comes up clean, I'm going to attribute it to goblins for now. Closing.