VOL-1691 Fix openolt adapter getting stuck while registartion with core

Change-Id: Ide8131f325bc15f1b909e14d7af6ee9bcd6b3b5b
diff --git a/vendor/github.com/armon/go-metrics/metrics.go b/vendor/github.com/armon/go-metrics/metrics.go
index cf9def7..4920d68 100644
--- a/vendor/github.com/armon/go-metrics/metrics.go
+++ b/vendor/github.com/armon/go-metrics/metrics.go
@@ -197,7 +197,7 @@
 	if labels == nil {
 		return nil
 	}
-	toReturn := labels[:0]
+	toReturn := []Label{}
 	for _, label := range labels {
 		if m.labelIsAllowed(&label) {
 			toReturn = append(toReturn, label)