grub installaion failed, then installer crashed (EFI)

[Norbert]

Using Ubuntu MATE 20.10 20200824, the problem with grub returned.
This bug is about EFI. Happened on latest version of QuickEMU with qemu-virgil 4.2.0.

```
Unable to install GRUB in /dev/vda (as superuser)

Executing 'grub-install /dev/vda' failed

This is fatal error.
```

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: ubiquity 20.10.9
ProcVersionSignature: Ubuntu 5.4.0-42.46-generic 5.4.44
Uname: Linux 5.4.0-42-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu44
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.452
Date: Mon Aug 24 11:17:46 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu-mate.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu-MATE 20.10 "Groovy Gorilla" - Alpha amd64 (20200824)
ProcEnviron:
 LANGUAGE=en_US.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Ubuntu QA Website (ubuntuqa)]

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1892687

[Norbert (nrbrtx)]

current builds are not affected anymore, seems fixed.