This bug was fixed in the package initramfs-tools - 0.130ubuntu6
--------------- initramfs-tools (0.130ubuntu6) cosmic; urgency=medium
* Fix formatting for the generated netplan config: headers were missing.
-- Mathieu Trudel-Lapierre <email address hidden> Thu, 10 May 2018 12:12:03 -0400
This bug was fixed in the package initramfs-tools - 0.130ubuntu6
---------------
initramfs-tools (0.130ubuntu6) cosmic; urgency=medium
* Fix formatting for the generated netplan config: headers were missing.
-- Mathieu Trudel-Lapierre <email address hidden> Thu, 10 May 2018 12:12:03 -0400