- Error out if anything that is not a PID is given
- Otherwise background all matching existing jobs, even if not all
PIDs exist (but print a message for the non-existing ones)
Fixes#3909.
The tests/*.status files aren't useful so eliminate them. Just verify whether
a given test module exited with a success status. There isn't any point in
having a "status" file that indicates the test module should exit with a
success (zero) status.
Closes#3208Closes#3209
