The test is functioning now, but it'd be good to know what has failed there.

Per @yusukes, these logs are related to the failure (but not the root cause)

2018-03-20T10:59:51.396712+00:00 ERR session_manager[24955]: [ERROR:object_proxy.cc(582)] Failed to call method: com.ubuntu.Upstart0_6.EmitEvent: object_path= /com/ubuntu/Upstart: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
2018-03-20T10:59:51.396948+00:00 ERR session_manager[24955]: [ERROR:session_manager_impl.cc(1959)] Emitting continue-arc-boot impulse failed.

arc-boot-continue.log ends with

[0320/035926:INFO:arc_setup.cc(1629)] Running !LaunchAndWait(command_line)... [0320/035951:FATAL:arc_setup.cc(1629)] Check failed: !(!LaunchAndWait(command_line)). /usr/lib64/libbase-core-395517.so(_ZN4base5debug10StackTraceC1Ev+0x13) [0x7bb523894553] Aborted (core dumped)

Other logs are here

https://pantheon.corp.google.com/storage/browser/chromeos-autotest-results/185047063-chromeos-test/chromeos2-row4-rack4-host7/cheets_StartAndroid.stress/sysinfo/var/log/

@yusuke promised to take a look, otherwise I have no clues.

/system/bin/arcbootcontinue execution failed for some reason, but logs from the command were lost. The command uses logcat (on memory buffer) for logging, but the container was shut down before auto test script tries to fetch the logs. Because of this, the reason of the failure is very unclear.

The command should probably use stderr for logging. Filed b/77155944 for that.

Another test failure:
https://luci-milo.appspot.com/buildbot/chromeos/reef-paladin/5437

#6 - is different: test is repeatedly restarting ui, and after the 2nd one the device has rebooted:

status.log:

Autotest client terminated unexpectedly: DUT rebooted during the test run.

tail of cheets_StartAndroid.stress.DEBUG

03/29 23:31:05.980 DEBUG|    cros_interface:0058| sh -c restart ui 
03/29 23:31:05.980 DEBUG|      global_hooks:0056| ['sh', '-c', 'restart ui']
<some garbage text follows>

> #6 - is different: test is repeatedly restarting ui, and after the 2nd one the device has rebooted:

Ah.  Can someone please file a new bug for the new failure?

unlabelling "ArcConstable".
This is now functioning on bots, so its out of scope of the constable tasks, I believe.