Also rewrite r.URL.Path, as gorilla mux reads this.

common/middleware/path_rewrite.go

@@ -21,6 +21,7 @@ type pathRewrite struct {
 func (p pathRewrite) Wrap(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		r.RequestURI = p.regexp.ReplaceAllString(r.RequestURI, p.replacement)
+		r.URL.Path = p.regexp.ReplaceAllString(r.RequestURI, p.replacement)
 		next.ServeHTTP(w, r)
 	})
 }