Install failed on btrfs

[PeggySue]

Installation failed at grub-install. Installing 16.04 to a btrfs partition with /data as a separate btrfs partition.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.41 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 4.3.0-2.11-generic 4.3.0
Uname: Linux 4.3.0-2-generic i686
ApportVersion: 2.19.3-0ubuntu2
Architecture: i386
CasperVersion: 1.366
Date: Sat Jan 16 12:38:51 2016
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash --- maybe-ubiquity
LiveMediaBuild: Ubuntu 16.04 LTS "Xenial Xerus" - Alpha i386 (20160104)
ProcEnviron:
 LANGUAGE=en_GB.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_GB.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.