cloud-images build process should not modify /etc/default/grub

[Scott Moser]

Thanks to bug 901600 and SRU to 12.04, we now no longer have to modify /etc/default/grub in the cloud-image build process.
That modification has caused a fair amount of fallout (usually wrt upgrading grub).

It would be nice to not do that any more.
Basically, lines 219 to ~ 260 [1] can be modified for precise or greater to not modify that file but add a /etc/default/grub.d/50-cloud-images.conf.

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[1] http://bazaar.launchpad.net/~ubuntu-on-ec2/vmbuilder/automated-ec2-builds/view/head:/vmbuilder-cloudimg-fixes#L219

Related bugs:
 * bug 901600: Allow /etc/default/grub overriding via /etc/default/grub.d/
 * bug 1009294: Grub update breaks automated dist-upgrade scripts on AMI images

[Ben Howard (darkmuggle-deactivatedaccount)]

Note: this only works with Grub 2.0 and later, not with Grub1.99. The commit in bug #901600 only applies to Grub versions in Quantal or later.

ubuntu@domU-12-31-39-14-76-2D:~$ sudo dpkg -l | grep grub
ii grub-common 1.99-21ubuntu3.9 GRand Unified Bootloader (common files)
ii grub-gfxpayload-lists 0.6 GRUB gfxpayload blacklist
ii grub-legacy-ec2 0.6.3-0ubuntu1.5 Handles update-grub for ec2 instances
ii grub-pc 1.99-21ubuntu3.9 GRand Unified Bootloader, version 2 (PC/BIOS version)
ii grub-pc-bin 1.99-21ubuntu3.9 GRand Unified Bootloader, version 2 (PC/BIOS binaries)
ii grub2-common 1.99-21ubuntu3.9 GRand Unified Bootloader (common files for version 2)