Matching on a str should compare content, not identity

[marijnh]

Either that, or we should disallow it altogether. The current behaviour, where you can put a str in a case pattern, but there's no way to guarantee that any other str will equal the literal you put in there, seems bogus.

[marijnh]

This was a nonsense issue. Matching actually does the right thing. I am unsure why == does a different thing, but that's another story.