Bug#916457: grub2-common: Grub refuses to re-enable IPv6 traffic

[Colin Watson]

On Sun, Dec 16, 2018 at 02:34:57PM +0000, Alan Reding wrote:
> Following your reply, I did a test which consisted of the following steps:
> 
> 1. I ran sudo gedit /etc/default/grub, deleted/removed GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 quiet", ran sudo update-grub and rebooted my machine.
> 
> 2. Immediately after the reboot, I issued the command nano /proc/cmdline and below is the result:
> 
> BOOT_IMAGE=/boot/vmlinuz-4.18.0-0.bpo.1-amd64 root=UUID=[string of alphanumeric characters] ro ipv6.disable=1 quiet
> 
> 3. Next, I ran the command sudo grep -RF ipv6.disable /etc and below is the result:
> 
> /etc/default/grub.ucf-old:#GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 quiet"
> /etc/default/grub:GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 quiet"
> 
> I am puzzled why ipv6.disable=1 quiet appears in the above results of (2) and (3) despite the fact that I had deleted/removed GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 quiet" from /etc/default/grub.

I'll need to see the full contents of /etc/default/grub and
/boot/grub/grub.cfg immediately after running step 1 above.  (No need to
reboot.)

-- 
Colin Watson                                       [cjwatson at debian.org]