milo: fix build/step timing

appengine/cmd/milo/swarming/build.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package swarming
 
 import (
         "bytes"
         "encoding/json"
         "fmt"
@@ skipping 235 matching lines @@
         }
 
         var err error
         if sr.StartedTs != "" {
                 build.Summary.Started, err = time.Parse(SwarmingTimeLayout, sr.StartedTs)
                 if err != nil {
                         return nil, fmt.Errorf("invalid task StartedTs: %s", err)
                 }
         }
         if sr.CompletedTs != "" {
-                build.Summary.Finished, err = time.Parse(SwarmingTimeLayout, sr.StartedTs)
+                build.Summary.Finished, err = time.Parse(SwarmingTimeLayout, sr.CompletedTs)
                 if err != nil {
                         return nil, fmt.Errorf("invalid task CompletedTs: %s", err)
                 }
         }
         if sr.Duration != 0 {
                 build.Summary.Duration = time.Duration(sr.Duration * float64(time.Second))
         } else if sr.State == TaskRunning {
                 now := clock.Now(c)
                 if build.Summary.Started.Before(now) {
                         build.Summary.Duration = now.Sub(build.Summary.Started)
@@ skipping 79 matching lines @@
 // Supports server aliases.
 func taskPageURL(swarmingHostname, taskID string) string {
         return fmt.Sprintf("https://%s/user/task/%s", swarmingHostname, taskID)
 }
 
 // botPageURL returns a URL to a human-consumable page of a swarming bot.
 // Supports server aliases.
 func botPageURL(swarmingHostname, botID string) string {
         return fmt.Sprintf("https://%s/restricted/bot/%s", swarmingHostname, botID)
 }