WP_Upgrader::delete_temp_backup()

	public function delete_temp_backup() {
		global $wp_filesystem;

		$errors = new WP_Error();

		foreach ( $this->temp_backups as $args ) {
			if ( empty( $args['slug'] ) || empty( $args['dir'] ) ) {
				return false;
			}

			if ( ! $wp_filesystem->wp_content_dir() ) {
				$errors->add( 'fs_no_content_dir', $this->strings['fs_no_content_dir'] );
				return $errors;
			}

			$temp_backup_dir = $wp_filesystem->wp_content_dir() . "upgrade-temp-backup/{$args['dir']}/{$args['slug']}";

			if ( ! $wp_filesystem->delete( $temp_backup_dir, true ) ) {
				$errors->add(
					'temp_backup_delete_failed',
					sprintf( $this->strings['temp_backup_delete_failed'] ),
					$args['slug']
				);
				continue;
			}
		}

		return $errors->has_errors() ? $errors : true;
	}