[errors] Greatly simplify common/errors package.

logdog/client/butler/streamserver/namedPipe_windows.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 streamserver
 
 import (
         "net"
 
         "golang.org/x/net/context"
 
         "github.com/luci/luci-go/common/errors"
         log "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/logdog/client/butlerlib/streamclient"
 
         "github.com/Microsoft/go-winio"
 )
 
 // maxWindowsNamedPipeLength is the maximum length of a Windows named pipe.
 const maxWindowsNamedPipeLength = 256
 
 // NewNamedPipeServer instantiates a new Windows named pipe server instance.
 func NewNamedPipeServer(ctx context.Context, name string) (StreamServer, error) {
         switch l := len(name); {
         case l == 0:
                 return nil, errors.New("cannot have empty name")
         case l > maxWindowsNamedPipeLength:
-                return nil, errors.Reason("name exceeds maximum length %(max)d").
-                        D("name", name).
-                        D("max", maxWindowsNamedPipeLength).
-                        Err()
+                return nil, errors.Reason("name exceeds maximum length %d", maxWindowsNamedPipeLength).
+                        InternalReason("name(%s)", name).Err()
         }
 
         ctx = log.SetField(ctx, "name", name)
         return &listenerStreamServer{
                 Context: ctx,
                 gen: func() (net.Listener, string, error) {
                         address := "net.pipe:" + name
                         pipePath := streamclient.LocalNamedPipePath(name)
                         log.Fields{
                                 "addr":     address,
                                 "pipePath": pipePath,
                         }.Debugf(ctx, "Creating Windows server socket Listener.")
 
                         l, err := winio.ListenPipe(pipePath, nil)
                         if err != nil {
-                                return nil, "", errors.Annotate(err).Reason("failed to listen on named pipe").Err()
+                                return nil, "", errors.Annotate(err, "failed to listen on named pipe").Err()
                         }
                         return l, address, nil
                 },
         }, nil
 }