Comment 0 for bug 1598136

In cloud image builds for each of powerpc and armhf (but not amd64, i386, ppc64el, arm64 or s390x) we see the following failure:

[2016-07-01 09:51:08] lb_binary_chroot
P: Begin copying chroot...
[2016-07-01 09:51:08] lb_binary_rootfs
P: Begin building root filesystem image...
0+0 records in
0+0 records out
0 bytes copied, 3.7116e-05 s, 0.0 kB/s
mke2fs 1.43.1 (08-Jun-2016)
ext2fs_check_if_mount: Can't check if filesystem is mounted due to missing mtab file while determining whether binary/boot/filesystem.ext4 is mounted.
Suggestion: Use Linux kernel >= 3.18 for improved stability of the metadata and journal checksum features.
Discarding device blocks: 4096/343040 done
Creating filesystem with 343040 4k blocks and 171600 inodes
Filesystem UUID: 43ff7fc9-12bb-4151-8549-77c8e1e35e2c
Superblock backups stored on blocks:
 32768, 98304, 163840, 229376, 294912

Allocating group tables: 0/11 done
Writing inode tables: 0/11 done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: 0/11 done

mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.

This is caused by this code in live-build's lb_binary_rootfs script:

dd if=/dev/zero of=binary/${INITFS}/filesystem.${LB_CHROOT_FILESYSTEM} bs=1024k count=0 seek=${REAL_DIM}
mkfs.${LB_CHROOT_FILESYSTEM} -F -b ${LB_EXT_BLOCKSIZE:-1024} -i 8192 -m 0 -L ${LB_HDD_LABEL} ${LB_EXT_RESIZEBLOCKS:+-E resize=${LB_EXT_RESIZEBLOCKS}} binary/${INITFS}/filesystem.${LB_CHROOT_FILESYSTEM}

mkdir -p filesystem.tmp
${LB_ROOT_COMMAND} mount -o loop binary/${INITFS}/filesystem.${LB_CHROOT_FILESYSTEM} filesystem.tmp