Milo: Prefetch logs that are failures

milo/appengine/logdog/logDogBuild.go

 // Copyright 2016 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 logdog
 
 import (
         "fmt"
         "time"
 
@@ skipping 59 matching lines @@
         default:
                 comp.Status = resp.NotRun
         }
 
         if !(buildCompletedTime.IsZero() || comp.Status.Terminal()) {
                 // The build has completed, but this step has not. Mark it as an
                 // infrastructure failure.
                 comp.Status = resp.InfraFailure
         }
 
-        // Hide the unimportant steps.
-        if comp.Status == resp.Success {
+        // Hide the unimportant steps, highlight the interesting ones.
+        switch comp.Status {
+        case resp.Success:
                 if _, ok := builtIn[anno.Name]; ok {
                         comp.Verbosity = resp.Hidden
                 }
+        case resp.InfraFailure, resp.Failure:
+                comp.Verbosity = resp.Interesting
         }
 
         // Main link is a link to the stdout.
         var stdoutLink *miloProto.Link
         if anno.StdoutStream != nil {
                 stdoutLink = &miloProto.Link{
                         Label: "stdout",
                         Value: &miloProto.Link_LogdogStream{
                                 LogdogStream: anno.StdoutStream,
                         },
@@ skipping 91 matching lines @@
         for _, prop := range mainAnno.Property {
                 propGroup.Property = append(propGroup.Property, &resp.Property{
                         Key:   prop.Name,
                         Value: prop.Value,
                 })
         }
         build.PropertyGroup = append(build.PropertyGroup, propGroup)
 
         return
 }