I just cloned the tip of master, still hitting this problem.

Do you want me to turn up debug and try this again?

2018-07-15 22:00:16.448 | dib-run-parts 95-package-uninstalls completed
2018-07-15 22:00:16.453 | dib-run-parts ----------------------- PROFILING -----------------------
2018-07-15 22:00:16.453 | dib-run-parts 
2018-07-15 22:00:16.465 | dib-run-parts Target: post-install.d
2018-07-15 22:00:16.465 | dib-run-parts 
2018-07-15 22:00:16.466 | dib-run-parts Script                                     Seconds
2018-07-15 22:00:16.467 | dib-run-parts ---------------------------------------  ----------
2018-07-15 22:00:16.468 | dib-run-parts 
2018-07-15 22:00:16.532 | dib-run-parts 00-package-installs                           0.374
2018-07-15 22:00:16.570 | dib-run-parts 95-package-uninstalls                         0.452
2018-07-15 22:00:16.583 | dib-run-parts 
2018-07-15 22:00:16.583 | dib-run-parts --------------------- END PROFILING ---------------------
2018-07-15 22:00:16.653 | Unmount /tmp/dib_build.iWopQLuO/mnt/var/cache/apt/archives
2018-07-15 22:00:16.683 | Unmount /tmp/dib_build.iWopQLuO/mnt/sys
2018-07-15 22:00:16.715 | Unmount /tmp/dib_build.iWopQLuO/mnt/proc
2018-07-15 22:00:16.739 | Unmount /tmp/dib_build.iWopQLuO/mnt/dev/pts
2018-07-15 22:00:16.779 | Unmount /tmp/dib_build.iWopQLuO/mnt/dev
2018-07-15 22:00:16.813 | Calculating image size (this may take a minute)...
2018-07-15 22:00:17.030 | INFO diskimage_builder.block_device.blockdevice [-] Wrote final block device config to [/tmp/dib_build.iWopQLuO/states/block-device/config.json]
2018-07-15 22:00:17.179 | INFO diskimage_builder.block_device.blockdevice [-] create() called
2018-07-15 22:00:17.179 | INFO diskimage_builder.block_device.level0.localloop [-] Create image file [/tmp/dib_image.aO8wYmAy/image0.raw]
2018-07-15 22:00:17.179 | INFO diskimage_builder.block_device.level0.localloop [-] loopdev attach
2018-07-15 22:00:17.219 | INFO diskimage_builder.block_device.level0.localloop [-] New block device [/dev/loop9]
2018-07-15 22:00:17.219 | INFO diskimage_builder.block_device.level1.partitioning [-] Creating partition on [image0] [/tmp/dib_image.aO8wYmAy/image0.raw]
2018-07-15 22:00:17.219 | INFO diskimage_builder.block_device.level1.mbr [-] Create MBR disk partitioning object
2018-07-15 22:00:17.219 | INFO diskimage_builder.block_device.level1.mbr [-] Partition absolute [2048] relative [0] length [204800] absolute end [206848]
2018-07-15 22:00:17.219 | INFO diskimage_builder.block_device.level1.mbr [-] Write partition entry blockno [0] entry [0] start [2048] length [204800]
2018-07-15 22:00:17.219 | INFO diskimage_builder.block_device.level1.mbr [-] Partition absolute [206848] relative [204800] length [3985408] absolute end [4192256]
2018-07-15 22:00:17.219 | INFO diskimage_builder.block_device.level1.mbr [-] Write partition entry blockno [0] entry [1] start [206848] length [3985408]
2018-07-15 22:00:17.220 | INFO diskimage_builder.block_device.utils [-] Calling [sudo sync]
2018-07-15 22:00:17.254 | INFO diskimage_builder.block_device.utils [-] Calling [sudo kpartx -avs /dev/loop9]
2018-07-15 22:00:17.259 | INFO diskimage_builder.block_device.level1.partitioning [-] Not creating the partitions a second time.
2018-07-15 22:00:17.259 | INFO diskimage_builder.block_device.utils [-] Calling [sudo mkfs -t ext4 -i 4096 -J size=64 -L root -U 1645159b-6d45-4ca9-8652-2ca0cf5a941e -q /dev/mapper/loop9p2]
2018-07-15 22:00:17.264 | ERROR diskimage_builder.block_device.blockdevice [-] Create failed; rollback initiated
2018-07-15 22:00:17.264 | Traceback (most recent call last):
2018-07-15 22:00:17.264 |   File "/usr/local/lib/python2.7/dist-packages/diskimage_builder/block_device/blockdevice.py", line 406, in cmd_create
2018-07-15 22:00:17.264 |     node.create()
2018-07-15 22:00:17.264 |   File "/usr/local/lib/python2.7/dist-packages/diskimage_builder/block_device/level2/mkfs.py", line 133, in create
2018-07-15 22:00:17.264 |     exec_sudo(cmd)
2018-07-15 22:00:17.264 |   File "/usr/local/lib/python2.7/dist-packages/diskimage_builder/block_device/utils.py", line 125, in exec_sudo
2018-07-15 22:00:17.264 |     ' '.join(sudo_cmd))
2018-07-15 22:00:17.264 | CalledProcessError: Command 'sudo mkfs -t ext4 -i 4096 -J size=64 -L root -U 1645159b-6d45-4ca9-8652-2ca0cf5a941e -q /dev/mapper/loop9p2' returned non-zero exit status 1
2018-07-15 22:00:17.264 | INFO diskimage_builder.block_device.level0.localloop [-] loopdev detach
2018-07-15 22:00:17.323 | INFO diskimage_builder.block_device.level0.localloop [-] Successfully detached [/dev/loop9]
2018-07-15 22:00:17.323 | INFO diskimage_builder.block_device.level0.localloop [-] Remove image file [/tmp/dib_image.aO8wYmAy/image0.raw]
2018-07-15 22:00:17.324 | ERROR diskimage_builder.block_device.blockdevice [-] Rollback complete, exiting
2018-07-15 22:00:17.324 | Traceback (most recent call last):