DIB fail to build ubuntu vm image

Failed to build a image with following this http://docs.openstack.org/developer/diskimage-builder/ with latest git tree.

commit 8c74c8e409adf21094a5973bef84a02ba8876464
Merge: b25044f b2c3a3a
Author: Jenkins <email address hidden>
Date: Tue Dec 6 03:18:58 2016 +0000

    Merge "Delete deprecated Hacking in tox.ini"

reproduce:

disk-image-create ubuntu vm

traces:
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 --------------------------------------- ----------
dib-run-parts Wed Dec 7 06:43:53 UTC 2016
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 00-disable-apt-recommends 0.005
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 00-remove-apt-xapian-index 1.925
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 00-remove-grub 0.022
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 01-dib-python 0.005
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 01-install-bin 0.007
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 01-set-ubuntu-mirror 5.125
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 02-add-apt-keys 0.005
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 02-package-installs 0.046
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 03-baseline-tools 4.696
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 04-dib-init-system 0.008
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 99-apt-get-update 2.611
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 99-package-uninstalls 0.049
dib-run-parts Wed Dec 7 06:43:53 UTC 2016
dib-run-parts Wed Dec 7 06:43:53 UTC 2016 --------------------- END PROFILING ---------------------
ERROR: unable to cleanly remove /tmp/dib_build.Lz5E3CET/mnt/tmp/in_target.d
Unmount /tmp/dib_build.Lz5E3CET/mnt/var/cache/apt/archives
Unmount /tmp/dib_build.Lz5E3CET/mnt/tmp/ccache
Unmount /tmp/dib_build.Lz5E3CET/mnt/sys
Unmount /tmp/dib_build.Lz5E3CET/mnt/proc
Unmount /tmp/dib_build.Lz5E3CET/mnt/dev/pts
Unmount /tmp/dib_build.Lz5E3CET/mnt/dev
ERROR: unable to cleanly remove /tmp/dib_build.Lz5E3CET/built
ubuntu@build-bot:~$ mount
/dev/vda1 on / type ext4 (rw)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/cgroup type tmpfs (rw)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
none on /run/user type tmpfs (rw,noexec,nosuid,nodev,size=104857600,mode=0755)
none on /sys/fs/pstore type pstore (rw)
systemd on /sys/fs/cgroup/systemd type cgroup (rw,noexec,nosuid,nodev,none,name=systemd)
tmpfs on /tmp/dib_build.18yA5axi type tmpfs (rw)
tmpfs on /tmp/dib_image.FRj3zdbQ type tmpfs (rw)
/home/ubuntu/.cache/image-create/ccache on /tmp/dib_build.18yA5axi/mnt/tmp/ccache type none (rw,bind)
tmpfs on /tmp/dib_build.fv0BCqvi type tmpfs (rw)
tmpfs on /tmp/dib_image.7U6S5bfC type tmpfs (rw)
tmpfs on /tmp/dib_build.ADy72SMl type tmpfs (rw)
tmpfs on /tmp/dib_image.cWzV4cVv type tmpfs (rw)
tmpfs on /tmp/dib_build.Lz5E3CET type tmpfs (rw)
tmpfs on /tmp/dib_image.dCuZUqJs type tmpfs (rw)