Plugin Update API: Set the translations key to an empty array when the API is unavailable. Props rmmcue. See #18200

git-svn-id: https://develop.svn.wordpress.org/trunk@25544 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/update.php

@@ -230,6 +230,7 @@ function wp_update_plugins() {
 		$new_option->translations = $response['translations'];
 	} else {
 		$new_option->response = array();
+		$new_option->translations = array();
 	}
 
 	set_site_transient( 'update_plugins', $new_option );