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

common/auth/localauth/server_test.go

Index: common/auth/localauth/server_test.go
diff --git a/common/auth/localauth/server_test.go b/common/auth/localauth/server_test.go
index 565735c91e12c64b5067b6576b2ecf32d1c4cefe..4d419b21cceb64bf3b74d193b396f5798d71db3b 100644
--- a/common/auth/localauth/server_test.go
+++ b/common/auth/localauth/server_test.go
@@ -21,6 +21,7 @@ import (
 	"github.com/luci/luci-go/common/clock"
 	"github.com/luci/luci-go/common/clock/testclock"
 	"github.com/luci/luci-go/common/errors"
+	"github.com/luci/luci-go/common/retry/transient"
 	"github.com/luci/luci-go/lucictx"
 
 	. "github.com/luci/luci-go/common/testing/assertions"
@@ -262,7 +263,7 @@ func TestProtocol(t *testing.T) {
 		})
 
 		Convey("Token generator returns transient error", func() {
-			responses <- errors.WrapTransient(fmt.Errorf("transient"))
+			responses <- errors.New("transient", transient.Tag)
 			So(call(goodRequest()), ShouldEqual, `HTTP 500: Transient error - transient`)
 		})
 	})