partman-auto-raid refuses to allow /boot inside raid + LVM when using preseed.cfg partman-auto/expert_recipe

Having /boot reside inside a logical volume as part of a mdraid mirror does work when configured manually, however it is impossible to preseed with partman-auto/expert_recipe.

At some point, preseeding "partman-auto-lvm/no_boot boolean true" started to allow /boot to be inside LVM - partman-auto-lvm-56ubuntu1/lib/auto-lvm.sh contains:
        # Make sure a boot partition isn't marked as lvmok, unless the user
        # has told us it is ok for /boot to reside on a logical volume
        if echo "$scheme" | grep lvmok | grep -q "[[:space:]]/boot[[:space:]]"; then
                db_input critical partman-auto-lvm/no_boot || true
                db_go || return 255
                db_get partman-auto-lvm/no_boot || true
                [ "$RET" = true ] || bail_out unusable_recipe
        fi
)

However, partman-auto-raid-30ubuntu1/display.d/initial_auto_raid_lvm doesn't allow exceptions, and /boot can not be inside an lvm on raid volumes:
# Make sure a boot partition isn't marked as lvmok
if echo "$scheme" | grep lvmok | grep -q "[[:space:]]/boot[[:space:]]"; then
        bail_out unusable_recipe
fi

Could a relaxed check similar to partman-auto-lvm be added to partman-auto-raid, so that /boot inside LVM inside mdraid can be preseeded as part of partman-auto/expert_recipe?

Thanks
James

d-i partman-auto/method string raid
d-i partman-auto/disk string /dev/sda /dev/sdb
d-i partman-auto-lvm/no_boot boolean true
d-i partman-auto-raid/recipe string \
        1 2 0 lvm - raidid=1 .
d-i partman-auto/expert_recipe string \
        myrecipe :: \
                1000 5000 40000 raid \
                        $lvmignore{ } \
                        $primary{ } \
                        method{ raid } \
                        raidid{ 1 } \
                . \
                1000 1000 1000 ext4 \
                        $defaultignore{ } \
                        $lvmok{ } \
                        method{ format } \
                        format{ } \
                        use_filesystem{ } \
                        filesystem{ ext4 } \
                        mountpoint{ /boot } \
                . \
                6000 6000 6000 ext4 \
                        $defaultignore{ } \
                        $lvmok{ } \
                        method{ format } \
                        format{ } \
                        use_filesystem{ } \
                        filesystem{ ext4 } \
                        mountpoint{ / } \
                .