I tried to run diagnose_cros_autotest.py (ToT bisect-kit):
export S=884587
export DUT=falco
./diagnose_cros_autotest.py --session=$S --old R71-11066.0.0 --new R71-11067.0.0 --board falco video_ChromeHWDecodeUsed.h264 $DUT

And it failed at bisect_cr_localbuild_internal. Here is the console log:
14:32:32 INFO chromeos_mirror = /usr/local/google/home/deanliao/git-mirrors/chromeos
14:32:32 INFO chromeos_root = /usr/local/google/home/deanliao/bisect-workdir/884587/chromeos
14:32:32 INFO chrome_mirror = /usr/local/google/home/deanliao/git-mirrors/chrome
14:32:32 INFO chrome_root = /usr/local/google/home/deanliao/bisect-workdir/884587/chrome
14:32:50 INFO bisect_cros_version old=R71-11066.0.0, new=R71-11067.0.0, done=True
14:32:50 INFO done
14:32:50 INFO bisect_cros_version old=R71-11066.0.0, new=R71-11067.0.0, done=True
14:32:50 INFO Range: (R71-11066.0.0, R71-11067.0.0], 1 revs left
14:32:50 INFO [0] R71-11066.0.0; {u'skip': 2, u'old': 1}
14:32:50 INFO [1] R71-11067.0.0; {u'new': 1}  <------------------
https://crosland.corp.google.com/log/11066.0.0..11067.0.0
14:32:50 INFO result R71-11066.0.0 R71-11067.0.0 None
14:32:53 INFO old: cros R71-11066.0.0, chrome 71.0.3544.0, android None
14:32:53 INFO new: cros R71-11067.0.0, chrome 71.0.3552.6, android None
14:33:16 INFO At least one version has no android. skip android bisect
14:33:16 INFO bisect chrome local build
14:33:16 INFO bisect_cr_localbuild_internal old=71.0.3544.0, new=71.0.3552.4~71.0.3552.5/6, done=False
14:33:16 INFO try idx=2778 rev=71.0.3552.6
14:33:16 ERROR exception in bisect_cr_localbuild_internal
Traceback (most recent call last):
  File "/usr/local/google/home/deanliao/bisect-kit/bisect_kit/diagnoser_cros.py", line 255, in narrow_down_chrome
    chrome_old, chrome_new, self.noisy = bisector.narrow_down()
  File "/usr/local/google/home/deanliao/bisect-kit/bisect_kit/wrapper.py", line 75, in narrow_down
    self.call('run')
  File "/usr/local/google/home/deanliao/bisect-kit/bisect_kit/wrapper.py", line 38, in call
    bisector.main(*full_args, prog=self.name)
  File "/usr/local/google/home/deanliao/bisect-kit/bisect_kit/cli.py", line 812, in main
    return opts.func(opts)
  File "/usr/local/google/home/deanliao/bisect-kit/bisect_kit/cli.py", line 440, in cmd_run
    step, status, values = self._switch_and_eval(rev, prev_rev=prev_rev)
  File "/usr/local/google/home/deanliao/bisect-kit/bisect_kit/cli.py", line 380, in _switch_and_eval
    status = do_switch(self.config['switch'], self.domain, rev)
  File "/usr/local/google/home/deanliao/bisect-kit/bisect_kit/cli.py", line 288, in do_switch
    domain.setenv(env, rev)
  File "/usr/local/google/home/deanliao/bisect-kit/bisect_cr_localbuild_internal.py", line 145, in setenv
    env['CHROME_MIRROR'] = self.config['chrome_mirror']
KeyError: 'chrome_mirror'