Description of problem:
Provisioning discovered host from engine takes first installation media in list but that media isn't associated with operating system in hostgroup.

2018-01-22 07:45:22 a544d7f0 [app] [I] Started PUT "/api/v2/discovered_hosts/mac525400106e16" for 192.168.100.59 at 2018-01-22 07:45:22 -0500
2018-01-22 07:45:22 a544d7f0 [app] [I] Processing by Api::V2::DiscoveredHostsController#update as JSON
2018-01-22 07:45:22 a544d7f0 [app] [I]   Parameters: {"discovered_host"=>{"name"=>"host-01", "hostgroup_id"=>"1", "environment_id"=>"1", "mac"=>"52:54:00:10:6e:16", "domain_id"=>"1", "subnet_id"=>"1", "ip"=>"192.168.100.26", "architecture_id"=>"1", "operatingsystem_id"=>"1", "medium_id"=>"9", "ptable_id"=>"61", "puppet_proxy_id"=>"1", "puppet_ca_proxy_id"=>"1", "root_pass"=>"[FILTERED]", "host_parameters_attributes"=>[{"name"=>"host_ovirt_id", "value"=>"[FILTERED]", "_destroy"=>"false"}, {"name"=>"compute_resource_id", "value"=>"[FILTERED]", "_destroy"=>"false"}, {"name"=>"pass", "value"=>"[FILTERED]", "_destroy"=>"false"}, {"name"=>"management", "value"=>"[FILTERED]", "_destroy"=>"false"}]}, "apiv"=>"v2", "id"=>"mac525400106e16"}
2018-01-22 07:45:22 a544d7f0 [app] [I] Authorized user admin(Admin User)
2018-01-22 07:45:22 a544d7f0 [app] [E] Unprocessable entity Host::Discovered (id: 31):
 |   Medium RHEL7.4 does not belong to RedHat 7.4 operating system


medium RHEL7.4 wasn't associated with RedHat 7.4 due to using synced image from subscriptions

manual provisioning in Satellite works

Version-Release number of selected component (if applicable):
Satellite 6.2.12
ovirt-engine-4.1.9.1-0.1.el7.noarch

How reproducible:
always

Steps to Reproduce:
1. have clean engine
2. in satellite have two media, alphabetically first isn't assocciated with operating system defined in host group
	
Actual results:
Cannot provision a host with different media until alphabetically first media was removed from

Expected results:
should provision only with associated media