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

server/auth/openid/method.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 openid
 
 import (
         "fmt"
         "net/http"
         "net/url"
         "path"
         "strings"
         "time"
 
         "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/logging"
+        "github.com/luci/luci-go/common/retry/transient"
         "github.com/luci/luci-go/server/auth"
         "github.com/luci/luci-go/server/router"
 )
 
 // These are installed into a HTTP router by AuthMethod.InstallHandlers(...).
 const (
         loginURL    = "/auth/openid/login"
         logoutURL   = "/auth/openid/logout"
         callbackURL = "/auth/openid/callback"
 )
@@ skipping 327 matching lines @@
                 cpy.MaxAge = -1
                 cpy.Expires = time.Unix(1, 0)
                 http.SetCookie(rw, &cpy)
         }
 }
 
 // replyError logs the error and replies with HTTP 500 (on transient errors) or
 // HTTP 400 on fatal errors (that can happen only on bad requests).
 func replyError(c context.Context, rw http.ResponseWriter, err error, msg string, args ...interface{}) {
         code := http.StatusBadRequest
-        if errors.IsTransient(err) {
+        if transient.Tag.In(err) {
                 code = http.StatusInternalServerError
         }
         msg = fmt.Sprintf(msg, args...)
         logging.Errorf(c, "HTTP %d: %s", code, msg)
         http.Error(rw, msg, code)
 }