Timeout following results collection

[jugglinmike]

Today, there was a failure in the process of collecting results for "chunk" 17 of 100 from the Edge browser. Unlike the issue reported in gh-564, this timeout occurred after the WPT process had completed. This process invokes the WPT CLI via a Python wrapper script which validates output and re-tries in the event of invalid/partial data. That wrapper script failed to exit properly. I have not yet identified the reason for this; very little processing occurs following the script's final output ("Found x results" / "Found y unexpected results" / "Found z missing results"), so I'm not sure what would interfere with termination. I will post more information here if this error occurs again.

Final lines of stalled process output (including Buildbot diagnostics)

2018-05-30 17:10:23,315 INFO validate-wpt-results wpt-run:stdout SUITE-END | took 896s
2018-05-30 17:10:23,330 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:23 - Got signal terminated
2018-05-30 17:10:23,339 INFO validate-wpt-results wpt-run:stdout Closing logging queue
2018-05-30 17:10:23,341 INFO validate-wpt-results wpt-run:stdout queue closed
2018-05-30 17:10:23,352 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:23 - Cleaning up.
2018-05-30 17:10:23,353 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:23 - Removing tunnel 5ffa1b0fda3a4861aa0bfd4ad0bf7c43.
2018-05-30 17:10:23,353 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:23 - Waiting for any active jobs using this tunnel to finish.
2018-05-30 17:10:23,353 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:23 - Press CTRL-C again to shut down immediately.
2018-05-30 17:10:23,353 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:23 - Note: if you do this, tests that are still running will fail.
2018-05-30 17:10:23,458 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:23 - Number of jobs using tunnel: 1.
2018-05-30 17:10:23,724 INFO validate-wpt-results WPT CLI exited with return code 1
2018-05-30 17:10:23,726 INFO validate-wpt-results Expected 60 results
2018-05-30 17:10:23,727 INFO validate-wpt-results Found 60 results
2018-05-30 17:10:23,727 INFO validate-wpt-results Found 0 unexpected results
2018-05-30 17:10:23,727 INFO validate-wpt-results Found 0 missing results
2018-05-30 17:10:31,357 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:31 - Number of jobs using tunnel: 1.
2018-05-30 17:10:38,159 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:38 - Number of jobs using tunnel: 1.
2018-05-30 17:10:43,797 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:43 - Number of jobs using tunnel: 1.
2018-05-30 17:10:51,022 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:51 - All jobs using the tunnel have finished.
2018-05-30 17:10:51,022 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:51 - Waiting for the connection to terminate...
2018-05-30 17:10:52,023 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:52 - Connection closed (8).
2018-05-30 17:10:52,023 INFO validate-wpt-results wpt-run:stdout 30 May 17:10:52 - Goodbye.

command timed out: 1200 seconds without output running ['run-and-verify.py', '--max-attempts', '3', '--log-wptreport', '/tmp/tmprBuk46/report.json', '--log-raw', '/tmp/tmprBuk46/log-raw.txt', '--', '--log-tbpl', '-', '--this-chunk', '63', '--total-chunks', '100', '--sauce-platform', 'windows 10', '--sauce-user', 'wpt-daisy', '--sauce-key', '<sauce_labs_key_daisy>', '--sauce-tunnel-id', 'daisy', '--sauce-connect-binary', 'sc', '--no-restart-on-unexpected', '--run-by-dir', '3', 'sauce:MicrosoftEdge:17'], attempting to kill
SIGKILL failed to kill process
using fake rc=-1
program finished with exit code -1

remoteFailed: [Failure instance: Traceback from remote host -- exceptions.RuntimeError: SIGKILL failed to kill process
]