redirect registry client output to stderr

Signed-off-by: Cyril Jouve <jv.cyril@gmail.com>
(cherry picked from commit 1535ad5)

cmd/helm/root.go

@@ -155,7 +155,7 @@ func newRootCmd(actionConfig *action.Configuration, out io.Writer, args []string
 	registryClient, err := registry.NewClient(
 		registry.ClientOptDebug(settings.Debug),
 		registry.ClientOptEnableCache(true),
-		registry.ClientOptWriter(out),
+		registry.ClientOptWriter(os.Stderr),
 		registry.ClientOptCredentialsFile(settings.RegistryConfig),
 	)
 	if err != nil {