fedora-atomic image fails to build using diskimage-builder>=2.4.0

See [1], the DIB project removed the variable DIB_ROOT_IMAGE_FS_UUID which is referenced by the magnum fedora-atomic element[2]. This causes the image to fail to build due to the use of 'set -u'. Using an older release of DIB (2.3.3) allows the image to be built successfully.

Tested using the following:

virtualenv venv
. venv/bin/activate
pip install -U pip
pip install diskimage-builder dib-utils
git clone https://git.openstack.org/openstack/magnum
export ELEMENTS_PATH=$(python -c 'import os, diskimage_builder, pkg_resources;print(os.path.abspath(pkg_resources.resource_filename(diskimage_builder.__name__, "elements")))')
export ELEMENTS_PATH="${ELEMENTS_PATH}:${PWD}/magnum/magnum/drivers/common/image"
export DIB_RELEASE=24
export DIB_IMAGE_SIZE=2.5
disk-image-create fedora-atomic -o fedora-atomic -x --no-tmpfs

Resulting output:

dib-run-parts Wed Jun 21 16:36:08 UTC 2017 Running /tmp/in_target.d/finalise.d/80-fedora-atomic
+ set -eu
+ set -o pipefail
+ cd /
+ ostree admin os-init fedora-atomic
ostree/deploy/fedora-atomic initialized as OSTree root
+ ostree remote add --set=gpg-verify=false fedora-atomic https://kojipkgs.fedoraproject.org/atomic/24/
+ ostree pull fedora-atomic d9c8b8a31238e857f010c6fdc282f5f611d3c8af3e78caa891f7edb85822771b
+ ostree remote delete fedora-atomic
+ ostree admin deploy --os=fedora-atomic d9c8b8a31238e857f010c6fdc282f5f611d3c8af3e78caa891f7edb85822771b --karg-proc-cmdline --karg=selinux=0
Relabeling /var (no stamp file '/ostree/deploy/fedora-atomic/var/.ostree-selabeled' found)
Transaction complete; bootconfig swap: yes deployment count change: 1
+ SYSROOT=/ostree/deploy/fedora-atomic/deploy/d9c8b8a31238e857f010c6fdc282f5f611d3c8af3e78caa891f7edb85822771b.0
+ cp /etc/fstab /ostree/deploy/fedora-atomic/deploy/d9c8b8a31238e857f010c6fdc282f5f611d3c8af3e78caa891f7edb85822771b.0/etc/
++ find /boot/ostree -name 'fedora-atomic-*' -type d
+ DEPLOYED_DIRECTORY=/boot/ostree/fedora-atomic-25c6c581906b39e21573b0d85f04c5d43021d3f28885101dcebeb8b31defee82
+ DEPLOYED_ID=25c6c581906b39e21573b0d85f04c5d43021d3f28885101dcebeb8b31defee82
++ find /boot/ostree/fedora-atomic-25c6c581906b39e21573b0d85f04c5d43021d3f28885101dcebeb8b31defee82 -name 'initramfs*.img'
+ INIT_IMAGE=/boot/ostree/fedora-atomic-25c6c581906b39e21573b0d85f04c5d43021d3f28885101dcebeb8b31defee82/initramfs-4.7.2-201.fc24.x86_64.img
++ find /boot/ostree/fedora-atomic-25c6c581906b39e21573b0d85f04c5d43021d3f28885101dcebeb8b31defee82 -name 'vmlinuz*'
+ VMLINUZ_IMAGE=/boot/ostree/fedora-atomic-25c6c581906b39e21573b0d85f04c5d43021d3f28885101dcebeb8b31defee82/vmlinuz
+ cat
/tmp/in_target.d/finalise.d/80-fedora-atomic: line 28: DIB_IMAGE_ROOT_FS_UUID: unbound variable

Installing diskimage-builder 2.3.3 allowed the image to be built successfully.
pip install diskimage-builder==2.3.3

[1] https://bugs.launchpad.net/diskimage-builder/+bug/1699273
[2] https://github.com/openstack/magnum/blob/907415c984e95e09a8b872f3c551ae6108c91de1/magnum/drivers/common/image/fedora-atomic/finalise.d/80-fedora-atomic#L30