Foreman is not able to provision a machine using an IP address already registered in the DNS.

Scenario:

• Create a host using network provisioning
• Use DCHP to attribute an IP address to the machine's interface
• Submit the creation

Now, Foreman may warn about a conflict for the DNS entry, something like "A PTR entry already exists for IP_ADDRESS/HOSTNAME.DOMAIN" (translation).

Now go back to the interface tab, push the overwrite button and foreman crashes with the following exception:

Net::Validations::Error
Invalid MAC
lib/net/validations.rb:40:in `validate_mac'
lib/net/dhcp/record.rb:7:in `initialize'
app/models/concerns/orchestration/dhcp.rb:19:in `new'
app/models/concerns/orchestration/dhcp.rb:19:in `dhcp_record'
app/models/concerns/orchestration/dhcp.rb:131:in `queue_remove_dhcp_conflicts'
app/models/concerns/orchestration/dhcp.rb:85:in `queue_dhcp'
app/models/concerns/orchestration.rb:48:in `valid?'
app/models/concerns/orchestration.rb:48:in `valid?'
app/models/concerns/foreman/sti.rb:29:in `save_with_type'
app/controllers/hosts_controller.rb:84:in `create'
app/controllers/concerns/application_shared.rb:13:in `set_timezone'
app/models/concerns/foreman/thread_session.rb:32:in `clear_thread'
lib/middleware/catch_json_parse_errors.rb:9:in `call'