I'm seeing pre-CQ failures which doesn't related to the CL in the pre-CQ.

e.g 
https://luci-milo.appspot.com/buildbot/chromiumos.tryserver/no_vmtest_pre_cq/197365
fails on BuildPackages for board reef
with :
https://logs.chromium.org/v/?s=chromeos%2Fbb%2Fchromiumos.tryserver%2Fno_vmtest_pre_cq%2F197365%2F%2B%2Frecipes%2Fsteps%2FBuildPackages%2F0%2Fstdout

chromeos-config-0.0.1-r9: Traceback (most recent call last):
chromeos-config-0.0.1-r9:   File "/usr/lib/python-exec/python2.7/cros_config_schema", line 9, in <module>
chromeos-config-0.0.1-r9:     load_entry_point('cros-config-host==1', 'console_scripts', 'cros_config_schema')()
chromeos-config-0.0.1-r9:   File "/usr/lib64/python2.7/site-packages/cros_config_host/v2/cros_config_schema.py", line 292, in main
chromeos-config-0.0.1-r9:     Main(args.schema, args.config, args.output, args.filter)
chromeos-config-0.0.1-r9:   File "/usr/lib64/python2.7/site-packages/cros_config_host/v2/cros_config_schema.py", line 278, in Main
chromeos-config-0.0.1-r9:     json_transform = TransformConfig(config_stream.read())
chromeos-config-0.0.1-r9:   File "/usr/lib64/python2.7/site-packages/cros_config_host/v2/cros_config_schema.py", line 118, in TransformConfig
chromeos-config-0.0.1-r9:     audio['files'] = _GetAudioFiles(model)
chromeos-config-0.0.1-r9:   File "/usr/lib64/python2.7/site-packages/cros_config_host/v2/cros_config_schema.py", line 138, in _GetAudioFiles
chromeos-config-0.0.1-r9:     card = model.audio.main.card
chromeos-config-0.0.1-r9: AttributeError: 'Config' object has no attribute 'card'
chromeos-config-0.0.1-r9:  * ERROR: chromeos-base/chromeos-config-0.0.1-r9::chromiumos failed (compile phase):
chromeos-config-0.0.1-r9:  *   Validation failed
chromeos-config-0.0.1-r9:  * 
chromeos-config-0.0.1-r9:  * Call stack:
chromeos-config-0.0.1-r9:  *     ebuild.sh, line  93:  Called src_compile
chromeos-config-0.0.1-r9:  *   environment, line 1281:  Called die
chromeos-config-0.0.1-r9:  * The specific snippet of code:
chromeos-config-0.0.1-r9:  *           cros_config_schema -c "${yaml}" -o "${json}" -f "True" || die "Validation failed";

Might be related to the CL:
https://chromium-review.googlesource.com/#/c/chromiumos/platform2/+/837151/