impl/prod: Fix logging field output.

impl/prod/logger.go

 // Copyright 2015 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 prod
 
 import (
         "fmt"
 
         "github.com/luci/luci-go/common/logging"
         "golang.org/x/net/context"
         "google.golang.org/appengine/log"
 )
 
 // useLogging adds a logging.Logger implementation to the context which logs to
 // appengine's log handler.
 func useLogging(c context.Context) context.Context {
         return logging.SetFactory(c, func(ic context.Context) logging.Logger {
-                return &loggerImpl{AEContext(ic)}
+                return &loggerImpl{AEContext(ic), ic}
         })
 }
 
 type loggerImpl struct {
         aeCtx context.Context
+        ic    context.Context
 }
 
 func (gl *loggerImpl) Debugf(format string, args ...interface{}) {
         gl.LogCall(logging.Debug, 1, format, args)
 }
 func (gl *loggerImpl) Infof(format string, args ...interface{}) {
         gl.LogCall(logging.Info, 1, format, args)
 }
 func (gl *loggerImpl) Warningf(format string, args ...interface{}) {
         gl.LogCall(logging.Warning, 1, format, args)
@@ skipping 16 matching lines @@
                 logf = log.Infof
         case logging.Warning:
                 logf = log.Warningf
 
         case logging.Error:
                 fallthrough
         default:
                 logf = log.Errorf
         }
 
-        fields := logging.GetFields(gl.aeCtx)
+        fields := logging.GetFields(gl.ic)
         if len(fields) > 0 {
                 logf(gl.aeCtx, "%s :: %s", fmt.Sprintf(format, args...), fields.FieldString(true))
         } else {
                 logf(gl.aeCtx, format, args...)
         }
 }