[errors] de-specialize Transient in favor of Tags.

tokenserver/appengine/impl/machinetoken/machinetoken.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 machinetoken implements generation of LUCI machine tokens.
 package machinetoken
 
 import (
         "crypto/x509"
         "encoding/base64"
         "fmt"
         "math"
         "math/big"
         "strings"
         "time"
 
         "github.com/golang/protobuf/proto"
         "golang.org/x/net/context"
 
         "github.com/luci/luci-go/common/clock"
-        "github.com/luci/luci-go/common/errors"
+        "github.com/luci/luci-go/common/retry/transient"
         "github.com/luci/luci-go/server/auth/signing"
 
         "github.com/luci/luci-go/tokenserver/api"
         "github.com/luci/luci-go/tokenserver/api/admin/v1"
         "github.com/luci/luci-go/tokenserver/appengine/impl/utils/tokensigning"
 )
 
 // tokenSigningContext is used to make sure machine token is not misused in
 // place of some other token.
 //
@@ skipping 87 matching lines @@
         if len(chunks) != 2 {
                 panic("impossible") // checked in Validate already
         }
         cfg := domainConfig(params.Config, chunks[1])
         if cfg == nil {
                 panic("impossible") // checked in Validate already
         }
 
         srvInfo, err := params.Signer.ServiceInfo(c)
         if err != nil {
-                return nil, "", errors.WrapTransient(err)
+                return nil, "", transient.Tag.Apply(err)
         }
 
         body := &tokenserver.MachineTokenBody{
                 MachineFqdn: params.FQDN,
                 IssuedBy:    srvInfo.ServiceAccountName,
                 IssuedAt:    uint64(clock.Now(c).Unix()),
                 Lifetime:    uint64(cfg.MachineTokenLifetime),
                 CaId:        params.Config.UniqueId,
                 CertSn:      params.Cert.SerialNumber.Uint64(), // already validated, fits uint64
         }
@@ skipping 47 matching lines @@
                 Lifespan: func(b proto.Message) tokensigning.Lifespan {
                         body := b.(*tokenserver.MachineTokenBody)
                         return tokensigning.Lifespan{
                                 NotBefore: time.Unix(int64(body.IssuedAt), 0),
                                 NotAfter:  time.Unix(int64(body.IssuedAt)+int64(body.Lifetime), 0),
                         }
                 },
         }
         return i.InspectToken(c, tok)
 }