Cross-linking: https://bugs.launchpad.net/curtin/+bug/1527664
IMHO, writing /etc/default/grub.d/50-curtin.cfg as: GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT <curtin specific options if any>" might work as a stop-gap solution so user modified /etc/default/grub will be also respected.
Cross-linking: https:/ /bugs.launchpad .net/curtin/ +bug/1527664
IMHO, writing /etc/default/ grub.d/ 50-curtin. cfg as: LINUX_DEFAULT= "$GRUB_ CMDLINE_ LINUX_DEFAULT <curtin specific options if any>"
GRUB_CMDLINE_
might work as a stop-gap solution so user modified /etc/default/grub will be also respected.