Extends xce-test-multihost's harness to submit one real job via plain
jobsub, sized (nproc+1 tasks, queried live) so it must span both
mh-worker-1 and mh-worker-2, poll jobinfo for RUN then DONE, and
confirm each allocated host's own log independently shows it starting
its share of the job's tasks.
The two allocated hosts take genuinely different code paths: the
controller sends startjob only to the head-node host
(dispatch_a_job_(), job.c); that host's job_start_remote_task()
relays a runtasks request back through the controller
(do_runtasks()/run_tasks_on_host(), task.c) to the other host, which
independently calls submit_fork_task(). The harness's per-host
verification accepts either line as legitimate evidence for that
host, since which host lands as head node is an allocator-internal
detail this test correctly doesn't hardcode.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XYdtrEWWZfKRRGED7raEYg