Fixing documents student visibility in a session see BT#1652

main/inc/lib/document.lib.php

@@ -485,6 +485,10 @@ class DocumentManager {
 		$current_session_id = api_get_session_id();
 		$condition_session = " AND (id_session = '$current_session_id' OR id_session = '0')";
         
+        if( !$can_see_invisible) {
+        	$condition_session = " AND (id_session = '$current_session_id' ) ";
+        }
+		
 		//condition for search (get ALL folders and documents)
 		if($search){
 			$sql = "SELECT docs.id, docs.filetype, docs.path, docs.title, docs.comment, docs.size, docs.readonly, docs.session_id, last.lastedit_date, last.visibility