unit-tests fail on armhf because of exec-bindpaths.service in test-execute

[Nick Rosbrook]

This autopkgtest log [1] shows the failure. The relevant part is:

1890s exec-bindpaths.service: Child 1662 belongs to exec-bindpaths.service.
1890s exec-bindpaths.service: Main process exited, code=exited, status=0/SUCCESS (success)
1890s exec-bindpaths.service: Running next main command for state start.
1890s exec-bindpaths.service: Will spawn child (service_run_next_main): test
1890s exec-bindpaths.service: Passing 0 fds to service
1890s exec-bindpaths.service: About to execute: test -f /tmp/thisisasimpletest
1890s Serializing sd-executor-state to memfd.
1890s exec-bindpaths.service: Forked test as 1664
1890s Closing set fd 18 (socket:[161184405])
1890s exec-bindpaths.service: Control group is empty.
1890s Received SIGCHLD from PID 1664 (test).
1890s Child 1664 (test) died (code=exited, status=0/SUCCESS)
1890s exec-bindpaths.service: Child 1664 belongs to exec-bindpaths.service.
1890s exec-bindpaths.service: Main process exited, code=exited, status=0/SUCCESS (success)
1890s exec-bindpaths.service: Running next main command for state start.
1890s exec-bindpaths.service: Will spawn child (service_run_next_main): test
1890s exec-bindpaths.service: Passing 0 fds to service
1890s exec-bindpaths.service: About to execute: test -f /tmp/test-exec-bindreadonlypaths/thisisasimpletest
1890s Serializing sd-executor-state to memfd.
1890s exec-bindpaths.service: Forked test as 1666
1890s Closing set fd 18 (socket:[161184405])
1890s Received SIGCHLD from PID 1666 (test).
1890s Child 1666 (test) died (code=exited, status=0/SUCCESS)
1890s exec-bindpaths.service: Child 1666 belongs to exec-bindpaths.service.
1890s exec-bindpaths.service: Main process exited, code=exited, status=0/SUCCESS (success)
1890s exec-bindpaths.service: Running next main command for state start.
1890s exec-bindpaths.service: Will spawn child (service_run_next_main): /bin/sh
1890s exec-bindpaths.service: Passing 0 fds to service
1890s exec-bindpaths.service: About to execute: /bin/sh -x -c "! touch /tmp/test-exec-bindreadonlypaths/thisisasimpletest"
1890s Serializing sd-executor-state to memfd.
1890s exec-bindpaths.service: Forked /bin/sh as 1668
1890s Closing set fd 18 (socket:[161184405])
1890s Received SIGCHLD from PID 1668 (sh).
1890s Child 1668 (sh) died (code=exited, status=0/SUCCESS)
1890s exec-bindpaths.service: Child 1668 belongs to exec-bindpaths.service.
1890s exec-bindpaths.service: Main process exited, code=exited, status=0/SUCCESS (success)
1890s exec-bindpaths.service: Running next main command for state start.
1890s exec-bindpaths.service: Will spawn child (service_run_next_main): rm
1890s exec-bindpaths.service: Passing 0 fds to service
1890s exec-bindpaths.service: About to execute: rm /tmp/thisisasimpletest
1890s Serializing sd-executor-state to memfd.
1890s exec-bindpaths.service: Forked rm as 1671
1890s Closing set fd 18 (socket:[161184405])
1890s Received SIGCHLD from PID 1671 (rm).
1890s Child 1671 (rm) died (code=exited, status=0/SUCCESS)
1890s exec-bindpaths.service: Child 1671 belongs to exec-bindpaths.service.
1890s exec-bindpaths.service: Main process exited, code=exited, status=0/SUCCESS (success)
1890s exec-bindpaths.service: Deactivated successfully.
1890s exec-bindpaths.service: Service will not restart (restart setting)
1890s exec-bindpaths.service: Changed start -> dead
1890s src/test/test-execute.c:261:test_exec_bindpaths: exec-bindpaths.service: can_unshare=no: exit status 0, expected 226
1890s (test-execute-unprivileged) terminated by signal ABRT.
1890s Assertion 'r >= 0' failed at src/test/test-execute.c:1330, function prepare_ns(). Aborting.

In particular, the test case expects this to unit *fail* with EXIT_NAMESPACE, but here it is succeeding.

[1] https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/armhf/s/systemd/20231215_033755_3c54f@/log.gz