Upgrade/Install: Check that WordPress is installed before scheduling …

…cleanup of the `temp-backup` directory.

Trying to schedule cron jobs before WordPress is installed results in DB errors, which is suboptimal.

This addresses a  `Table 'wp_options' doesn't exist` error when running the installation with `WP_DEBUG` enabled.

Follow-up to [51815], [51898], [51899], [51902], [52192].

Props dlh, pbiron.
See #51857.
Built from https://develop.svn.wordpress.org/trunk@52284


git-svn-id: http://core.svn.wordpress.org/trunk@51876 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-upgrader.php

@@ -141,7 +141,10 @@ public function __construct( $skin = null ) {
 	public function init() {
 		$this->skin->set_upgrader( $this );
 		$this->generic_strings();
-		$this->schedule_temp_backup_cleanup();
+
+		if ( ! wp_installing() ) {
+			$this->schedule_temp_backup_cleanup();
+		}
 	}
 
 	/**

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-52283';
+$wp_version = '5.9-alpha-52284';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.