Coming out of crbug.com/726171, in both cases these bisects failed while running the perf test.

Example:

https://uberchromegw.corp.google.com/i/internal.tryserver.clankium/builders/clankium-low-end-phone-perf-bisect/builds/316

Traceback (most recent call last):
  File "/home/chrome-bot/buildbot/build/third_party/twisted_10_2/twisted/internet/defer.py", line 290, in addCallbacks
    self._runCallbacks()
  File "/home/chrome-bot/buildbot/build/third_party/twisted_10_2/twisted/internet/defer.py", line 547, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/home/chrome-bot/buildbot/build/third_party/twisted_10_2/twisted/internet/defer.py", line 365, in callback
    self._startRunCallbacks(result)
  File "/home/chrome-bot/buildbot/build/third_party/twisted_10_2/twisted/internet/defer.py", line 459, in _startRunCallbacks
    self._runCallbacks()
--- <exception caught here> ---
  File "/home/chrome-bot/buildbot/build/third_party/twisted_10_2/twisted/internet/defer.py", line 547, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/home/chrome-bot/buildbot/build/scripts/master/chromium_step.py", line 1593, in onCommandFinished
    self.scriptComplete(command_result)
  File "/home/chrome-bot/buildbot/build/scripts/master/chromium_step.py", line 1583, in scriptComplete
    self.script_observer.handleReturnCode(cmd.rc)
  File "/home/chrome-bot/buildbot/build/scripts/master/chromium_step.py", line 1478, in handleReturnCode
    reason='return code was %d.' % return_code)
  File "/home/chrome-bot/buildbot/build/scripts/master/chromium_step.py", line 809, in finishCursor
    self.finishStep(self.cursor, status=status, reason=reason)
  File "/home/chrome-bot/buildbot/build/scripts/master/chromium_step.py", line 796, in finishStep
    section['log'].addHeader(msg)
  File "/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/status/logfile.py", line 462, in addHeader
    self.addEntry(HEADER, text)
  File "/home/chrome-bot/buildbot/build/third_party/buildbot_8_4p1/buildbot/status/logfile.py", line 414, in addEntry
    assert not self.finished
exceptions.AssertionError: