I see this on ToT:

FEATURES=test sudo -E emerge --nodeps -q chromeos-config-host


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ERROR: testMainWithExample (cros_config_host.v2.cros_config_schema_unittest.MainTests)
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Traceback (most recent call last):
  File "/var/tmp/portage/chromeos-base/chromeos-config-host-9999/work/chromeos-config-host-9999/chromeos-config/cros_config_host/v2/cros_config_schema_unittest.py", line 143, in testMainWithExample
    output)
  File "/var/tmp/portage/chromeos-base/chromeos-config-host-9999/work/chromeos-config-host-9999/chromeos-config/cros_config_host/v2/cros_config_schema.py", line 181, in Main
    ValidateConfigSchema(schema_stream.read(), json_transform)
  File "/var/tmp/portage/chromeos-base/chromeos-config-host-9999/work/chromeos-config-host-9999/chromeos-config/cros_config_host/v2/cros_config_schema.py", line 140, in ValidateConfigSchema
    validate(json_config, schema_json)
  File "/usr/lib64/python2.7/site-packages/jsonschema/validators.py", line 432, in validate
    cls(schema, *args, **kwargs).validate(instance)
  File "/usr/lib64/python2.7/site-packages/jsonschema/validators.py", line 117, in validate
    raise error
ValidationError: u'ucm-alsa-config-dir' is a required property

Failed validating u'required' in schema[u'properties'][u'models'][u'items'][u'properties'][u'audio'][u'properties'][u'main']:
    {u'additionalProperties': False,
     u'properties': {u'cras-config-dir': {u'description': u'Full path to cras config: /etc/cras/{cras-config-subdir} (Auto-generated)',
                                          u'pattern': u'^(/[^/ ]*)+/?$',
                                          u'type': u'string'},
                     u'cras-config-subdir': {u'description': u'Optional subdir for model specific configuration.',
                                             u'type': u'string'},
                     u'disable-profile': {u'description': u'Optional --disable_profile parameter for CRAS deamon.',
                                          u'type': u'string'},
                     u'ucm-suffix': {u'description': u'Optional UCM suffix used to determine model specific config.',
                                     u'type': u'string'}},
     u'required': [u'cras-config-dir', u'ucm-alsa-config-dir'],
     u'type': u'object'}

On instance[u'models'][0][u'audio'][u'main']:
    {u'cras-config-dir': u'/etc/cras/basking', u'ucm-suffix': u'basking'}

======================================================================
ERROR: testBasicSchemaValidation (cros_config_host.v2.cros_config_schema_unittest.ValidateConfigSchemaTests)
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Traceback (most recent call last):
  File "/var/tmp/portage/chromeos-base/chromeos-config-host-9999/work/chromeos-config-host-9999/chromeos-config/cros_config_host/v2/cros_config_schema_unittest.py", line 94, in testBasicSchemaValidation
    self._schema, cros_config_schema.TransformConfig(BASIC_CONFIG))
  File "/var/tmp/portage/chromeos-base/chromeos-config-host-9999/work/chromeos-config-host-9999/chromeos-config/cros_config_host/v2/cros_config_schema.py", line 140, in ValidateConfigSchema
    validate(json_config, schema_json)
  File "/usr/lib64/python2.7/site-packages/jsonschema/validators.py", line 432, in validate
    cls(schema, *args, **kwargs).validate(instance)
  File "/usr/lib64/python2.7/site-packages/jsonschema/validators.py", line 117, in validate
    raise error
ValidationError: u'ucm-alsa-config-dir' is a required property

Failed validating u'required' in schema[u'properties'][u'models'][u'items'][u'properties'][u'audio'][u'properties'][u'main']:
    {u'additionalProperties': False,
     u'properties': {u'cras-config-dir': {u'description': u'Full path to cras config: /etc/cras/{cras-config-subdir} (Auto-generated)',
                                          u'pattern': u'^(/[^/ ]*)+/?$',
                                          u'type': u'string'},
                     u'cras-config-subdir': {u'description': u'Optional subdir for model specific configuration.',
                                             u'type': u'string'},
                     u'disable-profile': {u'description': u'Optional --disable_profile parameter for CRAS deamon.',
                                          u'type': u'string'},
                     u'ucm-suffix': {u'description': u'Optional UCM suffix used to determine model specific config.',
                                     u'type': u'string'}},
     u'required': [u'cras-config-dir', u'ucm-alsa-config-dir'],
     u'type': u'object'}

On instance[u'models'][0][u'audio'][u'main']:
    {u'cras-config-dir': u'/etc/cras/basking', u'ucm-suffix': u'basking'}

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Ran 82 tests in 7.649s