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

common/errors/walk_test.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 errors
 
 import (
         "errors"
         "fmt"
         "testing"
@@ skipping 49 matching lines @@
                 } {
                         Convey(fmt.Sprintf(`Registers false for %T %v`, err, err), func() {
                                 So(Any(err, filter), ShouldBeFalse)
                         })
                 }
 
                 for _, err := range []error{
                         testErr,
                         MultiError{errors.New("other error"), MultiError{testErr, nil}},
                         Annotate(testErr).Reason("error test").Err(),
-                        WrapTransient(MultiError{WrapTransient(testErr), nil, errors.New("other error")}),
                 } {
                         Convey(fmt.Sprintf(`Registers true for %T %v`, err, err), func() {
                                 So(Any(err, filter), ShouldBeTrue)
                         })
                 }
         })
 }
 
 func TestContains(t *testing.T) {
         t.Parallel()
 
         Convey(`Testing the Contains function for a sentinel error`, t, func() {
                 sentinel := errors.New("test error")
 
                 for _, err := range []error{
                         nil,
                         errors.New("foo"),
                         errors.New("test error"),
                 } {
                         Convey(fmt.Sprintf(`Registers false for %T %v`, err, err), func() {
                                 So(Contains(err, sentinel), ShouldBeFalse)
                         })
                 }
 
                 for _, err := range []error{
                         sentinel,
                         MultiError{errors.New("other error"), MultiError{sentinel, nil}},
-                        WrapTransient(MultiError{WrapTransient(sentinel), nil, errors.New("other error")}),
                 } {
                         Convey(fmt.Sprintf(`Registers true for %T %v`, err, err), func() {
                                 So(Contains(err, sentinel), ShouldBeTrue)
                         })
                 }
         })
 }