On the other hand, maybe we should allow Ruby-level options to `system'
to raise, but continue hiding errors when running the command itself.

In other words:

	# continue old 1.8 behavior if redirect is done via shell
	# (n.b. this example is bad practice, but just an example)
	system('true >bad/file.txt') -> nil

So I think the original example by Dmitry should raise:

	system('true', out: %w(bad/file.txt w)) -> Errno...

Maybe this (potentially incompatible) change can be acceptable
for 2.2 (if not, then for Ruby 3.0)