Currently many requests unnecesarily get no batcache serving or headers set due to over-generic genlocks. At the moment a single genlock goves a url path, like `/wp/v2/posts`, which means any requests to `/wp/v2/posts?per_page=1` will not get cached, or send cache headers while the first request to `/wp/v2/posts` is processing.

I see no reason why genlocks and versions should not be tracked against the exact batcache cache key, rather than URL-only.