bug 2989: fix r26904

git-svn-id: http://piwigo.org/svn/branches/2.6@26906 68402e56-0260-453c-a942-63ccdbb3a9ee

admin/include/functions.php

@@ -785,6 +785,7 @@ function get_fulldirs($cat_ids)
   }
 
   // caching directories of existing categories
+  global $cat_dirs; // used in preg_replace callback
   $query = '
 SELECT id, dir
   FROM '.CATEGORIES_TABLE.'
@@ -824,6 +825,8 @@ SELECT id, uppercats, site_id
       );
   }
 
+  unset($cat_dirs);
+
   return $cat_fulldirs;
 }