Drop special 'back' case from response.redirect?
https://github.com/koajs/koa/blob/18dbf5f59c9f3e487e2b49c6dac483d1bed88974/lib/response.js#L254

expressjs/express#2692 is stuck. I thought, Koa is the future, so you may be more open to breaking changes. Sorry if I'm wrong.