Add 'sess_regenerate_destroy' setting
diff --git a/application/config/config.php b/application/config/config.php
index 1e39959..5b60ae9 100644
--- a/application/config/config.php
+++ b/application/config/config.php
@@ -344,6 +344,12 @@
 |
 |	How many seconds between CI regenerating the session ID.
 |
+| 'sess_regenerate_delete'
+|
+|	Whether to destroy session data associated with the old session ID
+|	when auto-regenerating the session ID. When set to FALSE, the data
+|	will be later deleted by the garbage collector.
+|
 | Other session cookie settings are shared with the rest of the application,
 | except for 'cookie_prefix' and 'cookie_httponly', which are ignored here.
 |
@@ -354,6 +360,7 @@
 $config['sess_save_path'] = NULL;
 $config['sess_match_ip'] = FALSE;
 $config['sess_time_to_update'] = 300;
+$config['sess_regenerate_destroy'] = FALSE;
 
 /*
 |--------------------------------------------------------------------------