Comment 8 for bug 1892290

Verified that focal grub2 with above commit works.
grub> linux vmlinuz-5.4.0-47-generic
grub> echo $?
0
grub> initrd initrd.img-5.4.0-47-generic
grub> echo $?
0

Rebuild grub2 deb with above commit and install
$ git clone -b applied/ubuntu/focal-updates https://git.launchpad.net/ubuntu/+source/grub2
$ cd grub2; git cherry-pick a6838bbc6726ad624bd2b94991f690b8e9d23c69 (which fetch from https://git.savannah.gnu.org/git/grub.git)
$ sudo apt-get build-dep grub2
$ dpkg-buildpackage -rfakeroot -b
$ cd ../; sudo apt install ./*.deb