doc/articles/wiki: fix path handling and clean up test process

Fixes #6525.

R=r
CC=golang-dev
https://golang.org/cl/14383043
diff --git a/doc/articles/wiki/final-noerror.go b/doc/articles/wiki/final-noerror.go
index e11d268..86d8da7 100644
--- a/doc/articles/wiki/final-noerror.go
+++ b/doc/articles/wiki/final-noerror.go
@@ -29,10 +29,8 @@
 	return &Page{Title: title, Body: body}, nil
 }
 
-const lenPath = len("/view/")
-
 func editHandler(w http.ResponseWriter, r *http.Request) {
-	title := r.URL.Path[lenPath:]
+	title := r.URL.Path[len("/edit/"):]
 	p, err := loadPage(title)
 	if err != nil {
 		p = &Page{Title: title}
@@ -42,7 +40,7 @@
 }
 
 func viewHandler(w http.ResponseWriter, r *http.Request) {
-	title := r.URL.Path[lenPath:]
+	title := r.URL.Path[len("/view/"):]
 	p, _ := loadPage(title)
 	t, _ := template.ParseFiles("view.html")
 	t.Execute(w, p)