Installer doesn't apply serial console grub options

Hi,

As long I can remember ubuntu, if installed over serial console redirection (console=ttyS0,115200), the installer would automatically add these keel option to the freshly installed GRUB.

I install over PXE, using the network installer keel & initrd.gz with the following commands.

#Ubuntu 16.04 LTS x86_64
LABEL ubuntu1604lts_64
MENU LABEL Ubuntu 16.04 LTS x86_64
KERNEL images/ubuntu/16.04LTS/x86_64/linux
APPEND tasks=standard pkgsel/language-pack-pattes= pkgsel/install-language-support=false text initrd=images/ubuntu/16.04LTS/x86_64/initrd.gz console=ttyS0,115200

Worked fine with 12.04/14.04, however I now install 16.04 and it doesn't.

Of course I solve this by not rebooting the system, executing a shell in the installer and manually updating the /boot/grub/grub.cfg.
Upon first boot adding it to /etc/default/grub and ruing update-grub, to make sure on upon keel update it won't be removed.

Is there something I need to add to the keel options of the installer of 16.04?
Eric