Comment 7 for bug 913336

I've attached "zfs-ubuntu-disable-recordfail.patch".

This supersedes my previous patches and takes a different approach. It disables the recordfail feature for filesystems to which GRUB cannot write (btrfs, zfs, etc.).

The changes from this patch are on top of (and should be folded into) debian/patches/ubuntu_failed_boot_menu.patch in the existing Ubuntu package.

This approach has the following benefits:
* On btrfs (and zfs, etc.), we don't show an error (and add delay) on every boot.
* We allow for the use of any and all features where GRUB only needs to *read* grubenv at boot.
* If the admin enables a different feature that uses save_env, it fails with an error rather than silently.