debian-build-cloud wheezy build failure on grub

gistfile1.txt

Configuring grub
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/umount /dev/pts
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/umount /sys
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/umount /proc
Executing: /bin/umount /target/af963f8b/root/dev
Executing: /bin/umount /target/af963f8b/root/boot
Executing: /bin/umount /target/af963f8b/root
Executing: /sbin/kpartx -d /dev/loop0
Executing: /sbin/dmsetup create vda
Executing: /sbin/kpartx -l /dev/mapper/vda
vda1 : 0 67553 /dev/mapper/vda 32
vda2 : 0 2048000 /dev/mapper/vda 67585
vda3 : 0 262143 /dev/mapper/vda 2115585
Executing: /sbin/kpartx -a /dev/mapper/vda
Executing: /bin/mount --types ext4 /dev/mapper/vda2 /target/af963f8b/root
Executing: /bin/mount --types ext2 /dev/mapper/vda1 /target/af963f8b/root/boot
Executing: /bin/mount --bind /dev /target/af963f8b/root/dev
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/mount --types proc none /proc
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/mount --types sysfs none /sys
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/mount --types devpts none /dev/pts
Executing: readlink -f /dev/mapper/vda
/dev/dm-0
Executing: readlink -f /dev/mapper/vda1
/dev/dm-1
Executing: readlink -f /dev/mapper/vda2
/dev/dm-2
Executing: readlink -f /dev/mapper/vda3
/dev/dm-3
Executing: /usr/sbin/chroot /target/af963f8b/root /usr/sbin/grub-install /dev/dm-0
/usr/sbin/grub-setup: warn: Your embedding area is unusually small.  core.img won't fit in it..
/usr/sbin/grub-setup: error: embedding is not possible, but this is required for cross-disk install.
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/umount /dev/pts
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/umount /sys
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/umount /proc
Executing: /bin/umount /target/af963f8b/root/dev
Executing: /bin/umount /target/af963f8b/root/boot
Executing: /bin/umount /target/af963f8b/root
Executing: /sbin/kpartx -d /dev/mapper/vda
Executing: /sbin/dmsetup remove vda
Executing: /sbin/kpartx -l /dev/loop0
loop0p1 : 0 67553 /dev/loop0 32
loop0p2 : 0 2048000 /dev/loop0 67585
loop0p3 : 0 262143 /dev/loop0 2115585
Executing: /sbin/kpartx -a /dev/loop0
Executing: /bin/mount --types ext4 /dev/mapper/loop0p2 /target/af963f8b/root
Executing: /bin/mount --types ext2 /dev/mapper/loop0p1 /target/af963f8b/root/boot
Executing: /bin/mount --bind /dev /target/af963f8b/root/dev
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/mount --types proc none /proc
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/mount --types sysfs none /sys
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/mount --types devpts none /dev/pts
Command '/usr/sbin/chroot /target/af963f8b/root /usr/sbin/grub-install /dev/dm-0' returned non-zero exit status 1
Traceback (most recent call last):
  File "/home/osallou/Desktop/build-debian-cloud/base/main.py", line 40, in run
    tasklist.run(info=bootstrap_info, dry_run=args.dry_run)
  File "/home/osallou/Desktop/build-debian-cloud/base/tasklist.py", line 30, in run
    task.run(info)
  File "/home/osallou/Desktop/build-debian-cloud/providers/virtualbox/tasks/boot.py", line 62, in run
    raise e
CalledProcessError: Command '/usr/sbin/chroot /target/af963f8b/root /usr/sbin/grub-install /dev/dm-0' returned non-zero exit status 1
Rolling back
Tasklist:
	<class 'common.tasks.filesystem.UnmountBoot'>
	<class 'common.tasks.filesystem.UnmountSpecials'>
	<class 'common.tasks.filesystem.UnmountRoot'>
	<class 'common.tasks.partitioning.UnmapPartitions'>
	<class 'common.tasks.volume.Detach'>
	<class 'common.tasks.filesystem.DeleteMountDir'>
	<class 'common.tasks.volume.Delete'>
	<class 'common.tasks.workspace.DeleteWorkspace'>
Unmounting the boot partition
Executing: /bin/umount /target/af963f8b/root/boot
Unmunting special block devices
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/umount /dev/pts
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/umount /sys
Executing: /usr/sbin/chroot /target/af963f8b/root /bin/umount /proc
Executing: /bin/umount /target/af963f8b/root/dev
Unmounting the bootstrap volume
Executing: /bin/umount /target/af963f8b/root
Removing volume partitions mapping
Executing: /sbin/kpartx -d /dev/loop0
Detaching the volume
Executing: /sbin/losetup --detach /dev/loop0
Deleting mountpoint for the bootstrap volume
Deleting the volume
Deleting workspace
Successfully completed rollback