Steps to reproduce:
* Install PureOS on Librem 15v3 using new ISO
* Do not modify /etc/default/grub
* apt update; apt upgrade
* (Update needs to include a GRUB update)
What should happen:
* GRUB (and other packages) update
What happens instead:
Seems to trigger `dpkg-reconfigure grub-pc` (or similar) and I am prompted to review changes as follows (the message states that this is because there have been local modifications, which I have not (knowingly) performed):
```
-GRUB_DISTRIBUTOR='PureOS'
+GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
-GRUB_ENABLE_CRYPTODISK=y
```
I opted to keep the local version, and was asked where I wanted GRUB installed:
* /dev/nvme0n1 (my boot drive)
* /dev/nvme0n1p1 (marked /boot, I'm guessing a partition on the boot drive)
* /dev/sda (second drive)
* /dev/dm-0 (looks like an encrypted partition)
I picked `/dev/nvme0n1` because this matches my memory of what I picked when installing. Reboot was successful.
My understanding is that this prompt should not have occurred, as I hadn't modified the grub file myself.