As part of the cache purging changes added in 1e3beb6e9, we should ignore our...

As part of the cache purging changes added in 1e3beb6e9, we should ignore our query string so caching isn't bypassed.

index-redis-page-cache.php

@@ -150,7 +150,7 @@ function redis_page_cache_get_clean_url() {
 			// Query strings create their own caches, so we reduce proliferation by ignoring certain common strings
 			$qs = '';
 			if ( ! empty( $_GET ) ) {
-				$ignore = array( 'c', 'flush', 'secret', 'utm_source', 'utm_medium', 'utm_term', 'utm_content', 'utm_campaign', 'fb_action_ids', 'fb_action_types', 'fb_ref', 'fb_source', 'fb_aggregation_id', );
+				$ignore = array( 'c', 'flush', 'secret', 'redis-page-cache-purge', 'utm_source', 'utm_medium', 'utm_term', 'utm_content', 'utm_campaign', 'fb_action_ids', 'fb_action_types', 'fb_ref', 'fb_source', 'fb_aggregation_id', );
 				$ignore = array_merge( $ignore, $redis_page_cache_config['query_strings_to_ignore'] );
 				$ignore = array_flip( $ignore );