Investigate flaky parallel/test-http-server-keep-alive-timeout

[Trott]

• Version: v10.0.0-pre (master)
• Platform: freebsd10-64
• Subsystem: test http

https://ci.nodejs.org/job/node-test-commit-freebsd/16985/nodes=freebsd10-64/console

not ok 783 parallel/test-http-server-keep-alive-timeout
  ---
  duration_ms: 2.29
  severity: fail
  exitcode: 1
  stack: |-
    Mismatched <anonymous> function calls. Expected exactly 3, actual 1.
        at Object.exports.mustCall (/usr/home/iojs/build/workspace/node-test-commit-freebsd/nodes/freebsd10-64/test/common/index.js:427:10)
        at serverEndKeepAliveTimeoutWithPipeline (/usr/home/iojs/build/workspace/node-test-commit-freebsd/nodes/freebsd10-64/test/parallel/test-http-server-keep-alive-timeout.js:22:43)
        at run (/usr/home/iojs/build/workspace/node-test-commit-freebsd/nodes/freebsd10-64/test/parallel/test-http-server-keep-alive-timeout.js:18:11)
        at process._tickCallback (internal/process/next_tick.js:172:11)
        at Function.Module.runMain (internal/modules/cjs/loader.js:721:11)
        at startup (internal/bootstrap/node.js:228:19)
        at bootstrapNodeJSCore (internal/bootstrap/node.js:575:3)
  ...

[Trott]

Stress test to see if it is reproducible:

https://ci.nodejs.org/job/node-stress-single-test/1816/

[Trott]

Stress test failed:

16:11:29 not ok 1 parallel/test-http-server-keep-alive-timeout
16:11:29   ---
16:11:29   duration_ms: 8.686
16:11:29   severity: fail
16:11:29   exitcode: 1
16:11:29   stack: |-
16:11:29     Mismatched <anonymous> function calls. Expected exactly 3, actual 0.
16:11:29         at Object.exports.mustCall (/usr/home/iojs/build/workspace/node-stress-single-test/nodes/freebsd10-64/test/common/index.js:427:10)
16:11:29         at serverEndKeepAliveTimeoutWithPipeline (/usr/home/iojs/build/workspace/node-stress-single-test/nodes/freebsd10-64/test/parallel/test-http-server-keep-alive-timeout.js:22:43)
16:11:29         at run (/usr/home/iojs/build/workspace/node-stress-single-test/nodes/freebsd10-64/test/parallel/test-http-server-keep-alive-timeout.js:18:11)
16:11:29         at process._tickCallback (internal/process/next_tick.js:172:11)
16:11:29         at Function.Module.runMain (internal/modules/cjs/loader.js:721:11)
16:11:29         at startup (internal/bootstrap/node.js:228:19)
16:11:29         at bootstrapNodeJSCore (internal/bootstrap/node.js:575:3)
16:11:29   ...