I'm trying to submit the following CL:
    https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/1171810

The change consistently fails in the moblab-generic-vm-pre-cq.
The symptom is that the AFE for the new image fails to answer.
Digging into the apache error logs, you can see this exception:
[Thu Aug 16 17:40:37.198322 2018] [:error] [pid 3709] [remote 127.0.0.1:0] ConfigError: Value 'stainless_url' not found in section 'AUTOTEST_WEB'

The change consists of two parts:
 1) Add a new config setting to global_config.ini
 2) Use the setting in server/lib/status_history.py

The error suggests that part 2) was built into the image on the
VM, but that part 1) failed to be installed.

I've already confirmed that there are no syntax errors in
the python code or the config file:  If you run the python
code standalone, it extracts the correct setting value.

I can't explain the behavior, but it looks like one of the
following must be happening:
 A) When the image is built, it doesn't contain all of the
    code changes.
 B) When the image is installed and booted on the VM, it
    loses the global_config.ini changes.

Based on preliminary testing with guado_moblab, I suspect
that the problem is B), but I don't have definitive proof.