Add new tests to presubmit, fix errors

go/login/login.go

 // login handles logging in users.
 package login
 
 // Theory of operation.
 //
 // We use OAuth 2.0 handle authentication. We are essentially doing OpenID
 // Connect, but vastly simplified since we are hardcoded to Google's endpoints.
 //
 // We do a simple OAuth 2.0 flow where the user is asked to grant permission to
 // the 'email' scope. See https://developers.google.com/+/api/oauth#email for
@@ skipping 244 matching lines @@
 //
 func StatusHandler(w http.ResponseWriter, r *http.Request) {
         glog.Infof("StatusHandler\n")
         w.Header().Set("Content-Type", "application/json")
         enc := json.NewEncoder(w)
         body := map[string]string{
                 "Email":    LoggedInAs(r),
                 "LoginURL": LoginURL(w, r),
         }
         if err := enc.Encode(body); err != nil {
-                glog.Errorf("Failed to encode Login status to JSON", err)
+                glog.Errorf("Failed to encode Login status to JSON: %s", err)
         }
 }