merge 2203 from branch-1_7 to trunk

- small correction (the prefetch of nezt image was not correct on non image pages generating 404 errors)

git-svn-id: http://piwigo.org/svn/trunk@2204 68402e56-0260-453c-a942-63ccdbb3a9ee

picture.php

@@ -494,7 +494,7 @@ $picture = trigger_event('picture_pictures_data', $picture);
 
 
 if (isset($picture['next']['image_url'])
-    and isset($picture['next']['is_picture']))
+    and $picture['next']['is_picture'] )
 {
   $template->assign_block_vars(
     'prefetch',