15.04 Installer crashes, can't handle mdadm imsm raid1

[John Center]

Using the desktop installer, had to manually purge dmraid & install mdadm with the grub-efi support. This always fails on the bootloader. Please fix this, we don't need dmraid for IMSM, only mdadm!

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: ubiquity 2.21.25
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
CasperVersion: 1.360
Date: Thu Aug 6 11:36:51 2015
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper nodmraid quiet splash ---
LiveMediaBuild: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)