Comment 5 for bug 530632

A little piece of extra information that may be useful. Before I start the do-release-upgrade the file /etc/modprobe.d/arch-aliases exists as a symlink to ./arch/i386 but something appears to be removing it before the update-initramfs runs resulting in the error and failed upgrade. This leaves the system unbootable, any attempts to reboot result in the machine getting dropped to the initramfs shell.