Attaching the debdiffs:
- upstart: Remove any reference to friendly-recovery from rcS.conf
- initramfs-tools: Add support for startup-event parameter (forwarded to init)
- grub2: Replace "single" by "startup-event=recovery-mode"
- friendly-recovery: Move from /usr to /lib, start from recovery-mode instead of single, split menu into read-only and read-write mode. See above for full changelog