fix headers sent erroneously with cache_modified_check and fetch()

NEWS

@@ -1,3 +1,5 @@
+  - fix headers sent erroneously with cache_modified_check and fetch()
+    (wphilips, messju)
   - fix config_file path bug (Marc Cabadas, Monte)
   - fix 'is even by' and 'is odd by' logic (Monte)
   - add day_empty, month_empty, year_empty and all_empty attributes to

libs/Smarty.class.php

@@ -1234,7 +1234,7 @@ class Smarty
                 }
             } else {
                 $this->_cache_info['template'][$resource_name] = true;
-                if ($this->cache_modified_check) {
+                if ($this->cache_modified_check && $display) {
                     header("Last-Modified: ".gmdate('D, d M Y H:i:s', time()).' GMT');
                 }
             }