Comment 8 for bug 508173

Sorry for the extended delay in response here. As soon as you asked for that information, I tried to reproduce it again on 10.04 a2 upgrade through to current daily but couldn't anymore. Due to other extenuating circumstances I wasn't able to run a full dist-upgrade from a 9.10 install with (hd0,3) preseeded until now.

I've made the change to install to install to the device node for the 10.04 based installs, so there shouldn't be any worries for those machines going forward.

Regarding why we're installing to the partition in the first place, it's because the MBR that's on the drive isn't a true DOS MBR, but something unique and specific to the factory processes. By the time it gets to the customer site and they break the electronic seal (press a key at the EULA on boot) it will begin behaving like a standard DOS MBR, referring to the active partition. Installing grub to the MBR would prevent this behavior.

So regarding my results from a 9.10 -> 10.04 upgrade, I just tried today from a fresh 9.10 install from an image preseeded with (hd0,3). Rather than it making a poor choice and behaving improperly, I was instead offered a dialog to choose where to install grub to. It appears to let me select where to install grub to. I'm sure this dialog will be rather shocking to anyone who received a system like this though, as they may have no idea that they were booting off the third partition. I'll attach a screenshot of this behavior to show.