juju get shows default value true

juju get shows default: true for every config option.

$ juju version
1.21-beta1-utopic-amd64

config.yaml snip for this charm:
  nagios_context:
    default: "juju"
    type: string
    description: |
      Used by the nrpe subordinate charms.
      A string that will be prepended to instance name to set the host name
      in nagios. So for instance the hostname would be something like:
         juju-myservice-0
      If you're running multiple environments with the same services in them
      this allows you to differentiate between them.
  nagios_servicegroups:
    default: ""
    type: string
    description: |
      A comma-separated list of nagios servicegroups.
      If left empty, the nagios_context will be used as the servicegroup.
  ingestion-mode:
    type: string
    default: "legacy"
    description: |
      How to run the charms and bundles ingestion in order to populate the
      database for this charm store. Possible values are:
      - none: charms/bundle ingestion is disabled;
      - legacy: all the charms/bundles revisions are synced with the legacy
        charmworlds and charm store;
      - launchpad: charms and bundles are ingested from Launchpad.
      Ingestion, if enabled, is run once the charmstore service is successfully
      related to elasticsearch and mongodb.
  ingestion-interval:
    type: int
    default: 15
    description: |
      The interval in minutes on which the ingestion is run, and new
      charms/bundles are imported into the charm store. Note that, if a
      previous ingestion job is still running, the current one is skipped.
      The default is used if the given value is <= 0.
  ingestion-concurrency:
    type: int
    default: 1
    description: |
      How many parallel processors must be used to run the ingestion.
      The default is used if the given value is <= 0.
  ingestion-loglevel:
    type: string
    default: "INFO"
    description: |
      The logging configuration to use when ingesting charms/bundles.
      For instance, to debug the ingestion process it is safe to set this
      value to "DEBUG". The log file can be found in
      /var/log/charmstore/charmload.log (in the charmstore units).
  ingestion-match:
    type: string
    default: ""
    description: |
      Only ingest charms whose IDs match the regular expression.
      By default all the charms and bundles are imported.

juju get for this charm:

$ juju get charmstore
charm: charmstore
service: charmstore
settings:
  ingestion-concurrency:
    default: true
    description: 'How many parallel processors must be used to run the ingestion.

      The default is used if the given value is <= 0.

'
    type: int
    value: 1
  ingestion-interval:
    default: true
    description: 'The interval in minutes on which the ingestion is run, and new

      charms/bundles are imported into the charm store. Note that, if a

      previous ingestion job is still running, the current one is skipped.

      The default is used if the given value is <= 0.

'
    type: int
    value: 15
  ingestion-loglevel:
    default: true
    description: 'The logging configuration to use when ingesting charms/bundles.

      For instance, to debug the ingestion process it is safe to set this

      value to "DEBUG". The log file can be found in

      /var/log/charmstore/charmload.log (in the charmstore units).

'
    type: string
    value: INFO
  ingestion-match:
    default: true
    description: 'Only ingest charms whose IDs match the regular expression.

      By default all the charms and bundles are imported.

'
    type: string
    value: ""
  ingestion-mode:
    default: true
    description: "How to run the charms and bundles ingestion in order to populate
      the\ndatabase for this charm store. Possible values are:\n- none: charms/bundle
      ingestion is disabled;\n- legacy: all the charms/bundles revisions are synced
      with the legacy\n charmworlds and charm store;\n- launchpad: charms and bundles
      are ingested from Launchpad.\nIngestion, if enabled, is run once the charmstore
      service is successfully\nrelated to elasticsearch and mongodb.\n"
    type: string
    value: legacy
  listen-port:
    default: true
    description: This is the tcp port on which the charmstore server will listen for
      connections.
    type: int
    value: 8080
  nagios_context:
    default: true
    description: "Used by the nrpe subordinate charms.\nA string that will be prepended
      to instance name to set the host name\nin nagios. So for instance the hostname
      would be something like:\n juju-myservice-0\nIf you're running multiple environments
      with the same services in them\nthis allows you to differentiate between them.\n"
    type: string
    value: juju
  nagios_servicegroups:
    default: true
    description: 'A comma-separated list of nagios servicegroups.

      If left empty, the nagios_context will be used as the servicegroup.

'
    type: string
    value: ""