satellite-installer command fails with - Failed to call refresh: Proxy satellite.example.com cannot be registered (500 Internal Server Error): N/A error when using DISA custom certificates

Issue

• satellite-installer fails with the following error being found in /var/log/foreman/production.log file:

/Stage[main]/Foreman_proxy::Register/Foreman_smartproxy[satellite.example.com]: Failed to call refresh: Proxy satellite.example.com cannot be registered (500 Internal Server Error): N/A

 /Stage[main]/Foreman_proxy::Register/Foreman_smartproxy[satellite.example.com]: Proxy satellite.example.com cannot be registered (500 Internal Server Error): N/A

 Marking certificate /root/ssl-build/satellite.example.com/satellite.example.com-apache for update
Marking certificate /root/ssl-build/satellite.example.com/satellite.example.com-foreman-proxy for update
Marking certificate /root/ssl-build/katello-server-ca for update
 /Stage[main]/Foreman_proxy::Register/Foreman_smartproxy[satellite.example.com]: Failed to call refresh: Proxy satellite.example.com cannot be registered (500 Internal Server Error): N/A
 /Stage[main]/Foreman_proxy::Register/Foreman_smartproxy[satellite.example.com]: Proxy satellite.example.com cannot be registered (500 Internal Server Error): N/A
Installing             Done                                               [100%] [......................................]
  Something went wrong! Check the log for ERROR-level output
  The full log is at /var/log/foreman-installer/satellite.log

• The /var/log/foreman/production.log file displays these messages at the same time the satellite-installer executed:

2018-04-24 09:46:10 11d2c8ae [app] [I] Started GET "/api/smart_proxies?search=name%3Dsatellite.example.com" for XXX.XXX.XXX.XXX at 2018-04-24 09:46:10 -0400
2018-04-24 09:46:10 11d2c8ae [app] [I] Processing by Api::V2::SmartProxiesController#index as JSON
2018-04-24 09:46:10 11d2c8ae [app] [I]   Parameters: {"search"=>"name=satellite.example.com", "apiv"=>"v2", "smart_proxy"=>{}}
2018-04-24 09:46:10 11d2c8ae [app] [I] Authorized user foreman_api_admin(API Admin)
2018-04-24 09:46:10 11d2c8ae [app] [I]   Rendered api/v2/smart_proxies/index.json.rabl within api/v2/layouts/index_layout (69.9ms)
2018-04-24 09:46:10 11d2c8ae [app] [I] Completed 200 OK in 134ms (Views: 82.9ms | ActiveRecord: 14.6ms)
2018-04-24 09:46:13 6514eed2 [app] [I] Started PUT "/api/smart_proxies/1/refresh" for XXX.XXX.XXX.XXX at 2018-04-24 09:46:13 -0400
2018-04-24 09:46:13 6514eed2 [app] [I] Processing by Api::V2::SmartProxiesController#refresh as JSON
2018-04-24 09:46:13 6514eed2 [app] [I]   Parameters: {"apiv"=>"v2", "id"=>"1", "smart_proxy"=>{}}
2018-04-24 09:46:13 6514eed2 [app] [I] Authorized user foreman_api_admin(API Admin)
2018-04-24 09:46:13 6514eed2 [app] [W] Action failed
 | ProxyAPI::ProxyException: ERF12-9411 [ProxyAPI::ProxyException]: Unable to fetch public key ([RestClient::InternalServerError]: 500 Internal Server Error) for Capsule https://satellite.example.com:9090/ssh
 | /opt/theforeman/tfm/root/usr/share/gems/gems/foreman_remote_execution-0.3.0.19/app/lib/proxy_api/remote_execution_ssh.rb:11:in `rescue in pubkey'
 | /opt/theforeman/tfm/root/usr/share/gems/gems/foreman_remote_execution-0.3.0.19/app/lib/proxy_api/remote_execution_ssh.rb:9:in `pubkey'
 | /opt/theforeman/tfm/root/usr/share/gems/gems/foreman_remote_execution-0.3.0.19/app/models/concerns/foreman_remote_execution/smart_proxy_extensions.rb:15:in `update_pubkey'
 | /opt/theforeman/tfm/root/usr/share/gems/gems/foreman_remote_execution-0.3.0.19/app/models/concerns/foreman_remote_execution/smart_proxy_extensions.rb:22:in `refresh_with_remote_execution'