Xubuntu 14.04 daily build failed to "grub-install sda sdb"

[Piete Brooks]

Installer reported failure and popped up window.
Asked it to try again, and the pointer changed to be spinning circle, but could still click buttons.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubiquity 2.17.2
ProcVersionSignature: Ubuntu 3.12.0-7.15-generic 3.12.4
Uname: Linux 3.12.0-7-generic x86_64
ApportVersion: 2.12.7-0ubuntu2
Architecture: amd64
CasperVersion: 1.336ubuntu1
Date: Wed Jan 8 08:57:20 2014
InstallCmdLine: file=/cdrom/preseed/xubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Xubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20131219)
ProcEnviron:
 LANGUAGE=en_GB.UTF-8
 TERM=linux
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_GB.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Phillip Susi (psusi)]

This looks like it may be a problem with the dmraid -> mdadm transition. How is that going Dmitri?