router: redirect repo.html and /repo/ to canonical `repo`

main.go

@@ -285,6 +285,22 @@ func (this *Application) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			this.Bannerpage(w, r, parts[1])
 
 		} else if parts := this.rxRepoPage.FindStringSubmatch(r.URL.Path); parts != nil {
+
+			// Support /repo.html URIs for backward compatibility
+			if strings.HasSuffix(parts[1], `.html`) {
+				w.Header().Set(`Location`, r.URL.Path[0:len(r.URL.Path)-5])
+				w.WriteHeader(301)
+				return
+			}
+
+			// The regexp supports an optional trailing slash
+			// Redirect to canonical no-trailing-slash
+			if strings.HasSuffix(r.URL.Path, `/`) {
+				w.Header().Set(`Location`, `/`+parts[1]) // n.b. parts[1] isn't urldecoded yet
+				w.WriteHeader(301)
+				return
+			}
+
 			this.Repopage(w, r, parts[1])
 
 		} else if r.URL.Path == `/static/logo.png` {