Yes, setting -Werror::ResourceWarning would indeed cause the test to fail again.

A couple of options we could potentially adopt:
1. Decide to ignore anything extra in the file anytime any kind of "error" filterwarning is present.
2. Decide to ignore anything extra in the file anytime "-Werror" is used because that is arguably the dominant, most common scenario where this issue comes up.
3. Decide that certain kinds of -Werror::SomeParticularWarning are worth paying attention to and others are not.
4. Decide that the ResourceWarning from _io itself needs to be properly dealt with.

Of those options, I do not like #1 and I think #3 is a slippery slope to step onto -- this patch pragmatically offers us #2 with the potential to pursue #4 (which is ultimately where I think we want this to go).  I kind of like the thought of someone specifying -Werror::ResourceWarning and getting to see this test fail.