Fix for the bug #1885: mysqldump does not dumps timestamp default.

sql/sql_parse.cc

@@ -3042,7 +3042,12 @@ bool add_field_to_list(char *field_name, enum_field_types type,
 
   if (default_value)
   {
-    if (default_value->type() == Item::NULL_ITEM)
+    if (type == FIELD_TYPE_TIMESTAMP)
+    {
+      net_printf(&thd->net, ER_INVALID_DEFAULT, field_name);
+      DBUG_RETURN(1);
+    }
+    else if (default_value->type() == Item::NULL_ITEM)
     {
       default_value=0;
       if ((type_modifier & (NOT_NULL_FLAG | AUTO_INCREMENT_FLAG)) ==