Bug 1613381

Description of problem:
the following used to work in 6.3 but no longer works in 6.4.0:

2018-08-04 05:26:58 - nailgun.client - DEBUG - Making HTTP GET request to https://qe-sat64-rhel7-tier1.satqe.lab.eng.rdu2.redhat.com/api/v2/audits with options {'data': '{"search": "type=subnet"}', 'auth': ('admin', 'changeme'), 'verify': False, 'headers': {'content-type': 'application/json'}}, no params and no data.
2018-08-04 05:26:58 - nailgun.client - WARNING - Received HTTP 400 response: {
  "error": {"message":"'auditable_type' should be one of 'role, ptable, provisioning_template, filter, katello/repository, hostgroup, smart_proxy, katello/host/content_facet, katello/host/subscription_facet, remote_execution_feature, lookup_value, model, domain, realm, environment, architecture, image, usergroup, hostgroup_class, puppetclass, medium, katello/content_view, katello/kt_environment, job_template, bookmark, katello/activation_key, katello/host_collection, katello/sync_plan, katello/capsule_lifecycle_environment, katello/content_view_component, katello/content_view_environment, katello/content_view_puppet_module, katello/content_view_version, katello/gpg_key, katello/product, foreman_virt_who_configure/config, job_invocation, ansible_role, foreman_openscap/policy, foreman_openscap/scap_content, foreman_openscap/tailoring_file, discovery_rule, compute_profile, config_group, config_group_class, ssh_key, compute_attribute, host_class, host_config_group, http_proxy, key_pair, personal_access_token, auth_source, compute_resource, host, interface, location, os, organization, override_value, partition_table, smart_class_parameter, smart_variable, parameter', but the query was 'subnet'","class":"ScopedSearch::QueryNotSupported"}
}

Version-Release number of selected component (if applicable):
6.4.0-16

How reproducible:
always