Killing the broker is destructive well beyond the units under test: nothing
reconnects to the new one, so logind for instance keeps running with
org.freedesktop.login1 unowned for the rest of the boot. As a subtest of
TEST-23-UNIT-FILE that leaked into everything running after it, and
statedir.sh, the first one to start user@0.service, then spent 25s per logind
property in user-runtime-dir and, where pam_systemd can't use Varlink, blocked
in CreateSession() past user@.service's 90s TimeoutStartSec and failed — with
the failure pointing at a subtest that has nothing to do with the bus.
In its own test the damage dies with the machine.