Comment 0 for bug 2009078

[Justification]
There is another round of security updates for secureboot that result in SBAT revocations of all the previous shims/grubs. Since the 20.04.5 point release inadvertently went out without a current UEFI bootloader and was thus already revoked before release, we have agreed to do an exceptional 20.04.6 point release. That should include the current version of shim and grub2.

[Test case]
* Build a daily PROPOSED=1 focal image that pulls in the new d-i boot bits.
* On a system with SecureBoot enabled, boot the 22.04.2 install media. This will cause SBAT to be updated and the system to refuse to boot older shims.
* Install secureboot-db 1.6~20.04.1 from focal-proposed, to force an update of dbx as well.
* Try to boot Ubuntu 20.04.5 media. Confirm that the boot is blocked with a security error.
* Boot the 20.04 daily media. Confirm that the image boots.

[Where problems could occur]
We are pulling grub2-signed and shim2-signed from focal-proposed. If something happens that prevents these from being released, then we would need to respin. Otherwise, this change should only increase the set of machines on which it's possible for us to boot the point release media.