I would like to contribute a patch for Foreman to fix an issue I have.

I need to provide some context: we use Foreman with Proxmox plugin.
This plugin fill the Foreman host with an upper-cased MAC address.

The MAC address is used by "Preseed finish template" (more precisely by 'preseed_networking_setup' snippet) to fill /etc/network/interfaces under Debian.

Unfortunately Debian requires a down-cased MAC address in this file.
So I modified this part to down-case @host.mac.

But it raises another issue: during provisioning MAC address changed (from upcase to downcase) so the final built request trig a DHCP reservation deletetion with the upcased MAC then create a new reservation using the downcased one, which raise an conflict error.

To fix theses issues, I made a patch to downcase mac address, so this address will be stable and usable directly by finish template.