Ensure that rewrite rules are flushed after clone.

We must make sure the database flags for already-flushed-rules
are not copied as part of the options table clone.

See #3371.

wp-content/themes/openlab/lib/course-clone.php

@@ -874,6 +874,8 @@ protected function migrate_site_settings() {
 			'fileupload_url',
 			'oplb_gradebook_db_version', // This will force reinstallation of tables.
 			'duplicate_post_version', // Forces duplicate-post to initialize roles
+			'openlab_rewrite_rules_flushed',
+			'openlab_modules_rewrite_rules_flushed', // Triggers rewrite rule flush post-clone.
 		);
 
 		$preserve_prefix = [