Upgrade/Install: Initialize the local `$checkout` variable in `WP_Automatic_Updater::is_vcs_checkout()`.

This avoids an `Undefined variable $checkout` PHP warning if all of the directories checked for access are disallowed due to the PHP `open_basedir` restrictions.

Follow-up to [55425].

Props jqz, costdev, audrasjb.
Fixes #58563.
Built from https://develop.svn.wordpress.org/trunk@56124


git-svn-id: http://core.svn.wordpress.org/trunk@55636 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-automatic-updater.php

@@ -148,6 +148,7 @@ class WP_Automatic_Updater {
 		}
 
 		$check_dirs = array_unique( $check_dirs );
+		$checkout   = false;
 
 		// Search all directories we've found for evidence of version control.
 		foreach ( $vcs_dirs as $vcs_dir ) {

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-beta2-56123';
+$wp_version = '6.3-beta2-56124';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.