Investigate flaky test test-child-process-emfile

[joaocgreis]

Examples of failures:

• pi2-raspbian-wheezy
• pi2-raspbian-wheezy (while testing v3.3.0)

Ref: #2636 (comment)

[joaocgreis]

Both happened in the new iojs-nodesource-raspbian-wheezy-pi2-7-mininodes

[joaocgreis]

Another one, again in pi2-7

[Fishrock123]

Why don't these tests show error output?

[rvagg]

rebooted pi2-7, just in case it's something related to just being set up yesterday and not having a reboot since

[skomski]

@Fishrock123 because they timed out - pr #2647 would make that visible

[jbergstroem]

Can't say I've seen this around either.

[joaocgreis]

Different platform: centos5-32: https://ci.nodejs.org/job/node-test-commit-linux/462/nodes=centos5-32/console

[Trott]

Seems to mostly/only fail on FreeBSD lately. #3335 isn't a fix but may at least help point someone in the right direction.