The registry's owner fence is the only access rule for a human kill: a job
is killable by the session whose list carries it, and a child session's own
jobs are no exception. The fence had pulled two implementation helpers out
of the Session Controller's package entry (plus a safe-host-export exception
for them) so the job controller could import them; both go, and the job
controller no longer depends on the agent registry or the Session Controller.
Yichen Jiang
0659ded55b