Taxonomy: Initialize `$noparents` variable in `wp_ajax_add_tag()` to avoid a notice with `compact()` in PHP 7.3.

Props pilou69.
Fixes #46670.
Built from https://develop.svn.wordpress.org/trunk@45034


git-svn-id: http://core.svn.wordpress.org/trunk@44843 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/ajax-actions.php

@@ -1027,7 +1027,9 @@ function wp_ajax_add_tag() {
 
 	$wp_list_table = _get_list_table( 'WP_Terms_List_Table', array( 'screen' => $_POST['screen'] ) );
 
-	$level = 0;
+	$level     = 0;
+	$noparents = '';
+
 	if ( is_taxonomy_hierarchical( $taxonomy ) ) {
 		$level = count( get_ancestors( $tag->term_id, $taxonomy, 'taxonomy' ) );
 		ob_start();

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.2-alpha-45033';
+$wp_version = '5.2-alpha-45034';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.