Small improvement in log_dir handling

program/lib/Roundcube/rcube.php

@@ -1303,7 +1303,6 @@ class rcube
         // log_driver == 'file' is assumed here
 
         $line = sprintf("[%s]: %s\n", $date, $line);
-        $log_dir = null;
 
         // per-user logging is activated
         if (self::$instance && self::$instance->config->get('per_user_logging') && self::$instance->get_user_id()) {
@@ -1312,12 +1311,15 @@ class rcube
                 return false;
             }
         }
-        else if (!empty($log['dir'])) {
+
+        if (empty($log_dir)) {
+            if (!empty($log['dir'])) {
                 $log_dir = $log['dir'];
             }
             else if (self::$instance) {
                 $log_dir = self::$instance->config->get('log_dir');
             }
+        }
 
         if (empty($log_dir)) {
             $log_dir = RCUBE_INSTALL_PATH . 'logs';