Move handler errors and path/signature splitting to handlers package

server/router.go

@@ -131,6 +131,9 @@ func (r *Router) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 			continue
 		}
 
+		// Set req.Pattern. We use it to trim path prefixes in handlers.
+		req.Pattern = rr.path
+
 		if !rr.silent {
 			LogRequest(reqID, req)
 		}