Return 409 error when uploading build with same number again

go/src/infra/appengine/test-results/frontend/upload.go

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package frontend
 
 import (
         "bytes"
         "encoding/json"
         "errors"
@@ skipping 261 matching lines @@
                 return statusError{err, http.StatusInternalServerError}
         }
 
         incr, err := f.AggregateResult()
         if err != nil {
                 logging.WithError(err).Errorf(c, "updateFullResults: convert to AggregateResult")
                 return statusError{err, http.StatusBadRequest}
         }
         if err := updateIncremental(c, &incr); err != nil {
                 logging.WithError(err).Errorf(c, "updateFullResults: updateIncremental")
-                return statusError{err, http.StatusInternalServerError}
+                code := http.StatusInternalServerError
+                if se, ok := err.(statusError); ok {
+                        code = se.code
+                }
+                return statusError{err, code}
         }
 
         p := GetUploadParams(c)
         wg := sync.WaitGroup{}
 
         wg.Add(1)
         go func() {
                 defer wg.Done()
                 if err := builderstate.Update(c, p.Master, p.Builder, p.TestType, time.Now().UTC()); err != nil {
                         // This isn't a fatal error; log at something less attention-seeking.
@@ skipping 268 matching lines @@
         }.Infof(c, "deleteKeys: enqueing")
 
         return taskqueue.Add(c, deleteKeysQueueName, &taskqueue.Task{
                 Path:    deleteKeysPath,
                 Payload: payload,
                 Header:  h,
                 Method:  "POST",
                 Delay:   time.Duration(30) * time.Minute,
         })
 }