The problem is that the factory image failed to build:

Traceback (most recent call last):
  File "/b/c/cbuild/repository/chromite/lib/parallel.py", line 442, in _Run
    self._task(*self._task_args, **self._task_kwargs)
  File "/b/c/cbuild/repository/chromite/cbuildbot/stages/artifact_stages.py", line 211, in BuildAndArchiveFactoryImages
    alias = commands.BuildFactoryInstallImage(buildroot, board, extra_env)
  File "/b/c/cbuild/repository/chromite/cbuildbot/commands.py", line 1994, in BuildFactoryInstallImage
    enter_chroot=True)
  File "/b/c/cbuild/repository/chromite/cbuildbot/commands.py", line 136, in RunBuildScript
    raise failures_lib.BuildScriptFailure(ex, cmd[0])
  File "/b/c/cbuild/repository/chromite/cbuildbot/commands.py", line 136, in RunBuildScript
    raise failures_lib.BuildScriptFailure(ex, cmd[0])
BuildScriptFailure: ./build_image failed (code=1)

Check the blamelist for changes that might have broken factory images,
and then pass the buck.

the blamelist:
https://crosland.corp.google.com/log/10569.1.0..10575.0.0

I believe that only two commits related to this error:
1. commands.py, CL: https://chromium-review.googlesource.com/998981
2. artifact_stages.py,  CL: https://chromium-review.googlesource.com/996564

Probably the second one triggered the issue. 
cc-ed the first one author.

This isn't related to CL:998981.  It doesn't look related to CL:996564 either.  It looks to me like another instance of crbug.com/796254.

Yeah, this isn't caused by a chromite change.  The blamelist has four changes
to src/platform/factory, and one more to src/platform/factory-private.  Any
one of those might conceivably cause a problem, but it looks far more likely
that this is a duplicate of bug 796254.

If it's actually a duplicate, I think the problem should show itself as flake;
that is, it will succeed with the next build.

Might be similar to the issue with setzer as well. That looked like a one-time occurrence, so I didn't create a bug for that yet.

Failed to mount all partitions in /mnt/host/source/src/build/images/setzer/R67-10575.0.0-a3/factory_install_shim.bin

I agree with Hungte, probably a dup of bug 796254.

I meant, agree with Richard...

Removing myself as owner; my change had nothing to do with this.

factory_install_shim is built by 'build_image factory_install', which uses resources mainly from initramfs, src/platform/factory_installer.

All the changes to src/platform/factory listed there are not related to building factory_install. Also, factory-private is a repo not used by any ebuilds yet (that's why we're cleaning it up).

So unless this keeps happening, I think it's not related to those changes.

Not an infra problem