ubiquity crashed during install on md raid1

[John Center]

My system is UEFI. I am installing Ubuntu 16.04 desktop on btrfs on top of mdadm raid1. Installer failed when trying to install grub-efi-amd64-bin.

root@ubuntu:/opt/build/btrfs-progs# lsb_release -rd
Description: Ubuntu 16.04 LTS
Release: 16.04

root@ubuntu:/opt/build/btrfs-progs# apt-cache policy grub-efi-amd64-bin
grub-efi-amd64-bin:
  Installed: 2.02~beta2-36ubuntu3
  Candidate: 2.02~beta2-36ubuntu3
  Version table:
 *** 2.02~beta2-36ubuntu3 500
        500 cdrom://Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1) xenial/main amd64 Packages
        500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status

I expected the installer to complete or fail to install grub2. I didn't expect it to crash.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.63.1 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CasperVersion: 1.376
Date: Sun May 29 17:35:25 2016
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash ---
LiveMediaBuild: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Phillip Susi (psusi)]

Looks like this is an Intel fakeraid and that they don't seem to be working right since the dmraid -> mdadm transition.