Created attachment 1042491 [details]
Output of foreman-debug from a Satellite 6.1.0 system running RHEL 7.1.

Description of problem:
It is possible to trigger an HTTP 500 error by issing an HTTP PUT request to
`/api/v2/hosts/:id` and attempting to update any of the following attributes:

* capabilities
* puppet_class

The following JSON messages are returned by the server:

    {"error": {"message":"unknown attribute: capabilities"}}
    {"error": {"message":"unknown attribute: puppet_class_ids"}}

Here's a full example:

    >>> from nailgun import entities
    >>> host = entities.Host(id=13).read()
    >>> host.name = 'foo'
    >>> host.update_payload()
    {
        u'host': {
            'architecture_id': 43,
            'build': False,
            'capabilities': [u'build'],
            'compute_profile_id': None,
            'compute_resource_id': None,
            'domain_id': 60,
            'enabled': True,
            'environment_id': 228,
            'host_parameters_attributes': [],
            'hostgroup_id': None,
            'id': 13,
            'image_id': None,
            'ip': None,
            'location_id': 460,
            'mac': u'd9:3e:f2:ba:fa:9a',
            'managed': True,
            'medium_id': 50,
            'model_id': None,
            'name': 'foo',
            'operatingsystem_id': 66,
            'organization_id': 459,
            'owner_id': 3,
            'owner_type': u'User',
            'provision_method': u'build',
            'ptable_id': 38,
            'puppet_class_ids': [],
            'puppet_proxy_id': None,
            'realm_id': None,
            'subnet_id': None,
        }
    }
    >>> response = host.update_raw()
    WARNING:nailgun.client:Received HTTP 500 response: {
        "error": {"message":"unknown attribute: capabilities"}
    }

    >>> fields = set(host.get_fields().keys())
    >>> fields.remove('root_pass')
    >>> fields.remove('capabilities')
    >>> host.update_payload(fields)
    {
        u'host': {
            'architecture_id': 43,
            'build': False,
            'compute_profile_id': None,
            'compute_resource_id': None,
            'domain_id': 60,
            'enabled': True,
            'environment_id': 228,
            'host_parameters_attributes': [],
            'hostgroup_id': None,
            'id': 13,
            'image_id': None,
            'ip': None,
            'location_id': 460,
            'mac': u'd9:3e:f2:ba:fa:9a',
            'managed': True,
            'medium_id': 50,
            'model_id': None,
            'name': u'sdycruihg.fymn8dotb0',
            'operatingsystem_id': 66,
            'organization_id': 459,
            'owner_id': 3,
            'owner_type': u'User',
            'provision_method': u'build',
            'ptable_id': 38,
            'puppet_class_ids': [],
            'puppet_proxy_id': None,
            'realm_id': None,
            'subnet_id': None,
        }
    }
    >>> response = host.update_raw(fields)
    WARNING:nailgun.client:Received HTTP 500 response: {
        "error": {"message":"unknown attribute: puppet_class_ids"}
    }

    >>> fields.remove('puppet_class')
    >>> response = host.update_raw(fields)
    WARNING:nailgun.client:Received HTTP 422 response: {
        "error": {"id":13,"errors":{"provision_method":["can't be updated after host is provisioned"]},"full_messages":["Provision method can't be updated after host is provisioned"]}
    }

    >>> fields.remove('provision_method')
    >>> response = host.update_raw(fields)
    >>> response.status_code
    200

Version-Release number of selected component (if applicable):
Satellite 6.1.0. Foreman-debug is attached.

How reproducible:
100%

Steps to Reproduce:
1. See "Description of problem" section.
2.
3.

Actual results:
See "Description of problem" section.

Expected results:
See "Description of problem" section.

Additional info: