systemd-nspawn doesn't like invalid machine IDs and refuses to boot with one:
TEST-74-AUX-UTILS RUN: Tests for auxiliary utilities
...
Spawning container TEST-74-AUX-UTILS--3 on /var/tmp/systemd-test-TEST-74-AUX-UTILS_3/root.
Press Ctrl-] three times within 1s to kill container.
Failed to read machine ID from container image: Structure needs cleaning
E: nspawn failed with exit code 1
Follow-up to b4d42a82eb.
Mike Yuan
Frantisek Sumsal