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

common/auth/internal/disk_cache.go

Index: common/auth/internal/disk_cache.go
diff --git a/common/auth/internal/disk_cache.go b/common/auth/internal/disk_cache.go
index 27a5ce53e2a8015c3c9a750f495a316a0d52910b..eae18f796434a087fbfd14e5bed5a98a4c0b28fe 100644
--- a/common/auth/internal/disk_cache.go
+++ b/common/auth/internal/disk_cache.go
@@ -15,7 +15,6 @@ import (
 	"golang.org/x/oauth2"
 
 	"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"
 )
@@ -198,7 +197,7 @@ func (c *DiskTokenCache) writeCacheFile(cache *cacheFile, now time.Time) error {
 	// a retry in updateCacheFile.
 	if err = os.Rename(tmp.Name(), c.absPath()); err != nil {
 		cleanup()
-		return errors.WrapTransient(err)
+		return retry.Tag.Apply(err)
 	}
 	return nil
 }