investigate flaky test-net-connect-handle-econnrefused

[Trott]

https://ci.nodejs.org/job/node-test-commit-linux/26401/nodes=debian8-64/console

test-rackspace-debian8-x64-1

11:09:03 not ok 1277 parallel/test-net-connect-handle-econnrefused
11:09:03 ---
11:09:03 duration_ms: 0.143
11:09:03 severity: fail
11:09:03 exitcode: 1
11:09:03 stack: |-
11:09:03 assert.js:129
11:09:03 throw err;
11:09:03 ^
11:09:03 
11:09:03 AssertionError [ERR_ASSERTION]: function should not have been called at /home/iojs/build/workspace/node-test-commit-linux/nodes/debian8-64/test/parallel/test-net-connect-handle-econnrefused.js:32
11:09:03 at Socket.mustNotCall (/home/iojs/build/workspace/node-test-commit-linux/nodes/debian8-64/test/common/index.js:416:12)
11:09:03 at Socket.emit (events.js:194:13)
11:09:03 at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1046:10)
11:09:03 ...