CentOS 7 and 8 build fails when including a /usr partition

[Joshua Slater]

Whenever a /usr partition is included in the block device configuration for a CentOS 7 or 8 image, the image build fails.

diskimage-builder version: 3.3.1

Command: disk-image-create block-device-mbr centos vm -o testimage --logfile testlog

Environment variables:
DIB_RELEASE=7 (also fails when unset)
DIB_BLOCK_DEVICE_CONFIG=file:///home/jslater/dib/block-device.yaml (attached)

Noticed an anomalous log line that doesn't normally occur:

chroot: failed to run command '/usr/sbin/setfiles': No such file or directory

Resulting failure (full log is attached):
2020-10-05 18:43:15.088 | INFO diskimage_builder.block_device.utils [-] Calling [sudo kpartx -d /dev/loop0]
2020-10-05 18:43:15.149 | Traceback (most recent call last):
2020-10-05 18:43:15.149 | File "/usr/local/bin/dib-block-device", line 11, in <module>
2020-10-05 18:43:15.149 | sys.exit(main())
2020-10-05 18:43:15.149 | File "/usr/local/lib/python3.6/site-packages/diskimage_builder/block_device/cmd.py", line 120, in main
2020-10-05 18:43:15.149 | return bdc.main()
2020-10-05 18:43:15.149 | File "/usr/local/lib/python3.6/site-packages/diskimage_builder/block_device/cmd.py", line 115, in main
2020-10-05 18:43:15.149 | self.args.func()
2020-10-05 18:43:15.149 | File "/usr/local/lib/python3.6/site-packages/diskimage_builder/block_device/cmd.py", line 39, in cmd_umount
2020-10-05 18:43:15.149 | self.bd.cmd_umount()
2020-10-05 18:43:15.149 | File "/usr/local/lib/python3.6/site-packages/diskimage_builder/block_device/blockdevice.py", line 442, in cmd_umount
2020-10-05 18:43:15.149 | node.umount()
2020-10-05 18:43:15.149 | File "/usr/local/lib/python3.6/site-packages/diskimage_builder/block_device/level1/partition.py", line 88, in umount
2020-10-05 18:43:15.149 | self.partitioning.umount()
2020-10-05 18:43:15.149 | File "/usr/local/lib/python3.6/site-packages/diskimage_builder/block_device/level1/partitioning.py", line 228, in umount
2020-10-05 18:43:15.149 | self.state['blockdev'][self.base]['device']])
2020-10-05 18:43:15.149 | File "/usr/local/lib/python3.6/site-packages/diskimage_builder/block_device/utils.py", line 143, in exec_sudo
2020-10-05 18:43:15.149 | raise e
2020-10-05 18:43:15.149 | diskimage_builder.block_device.exception.BlockDeviceSetupException: exec_sudo failed