Skip padding when id is empty string

site-generator

@@ -303,7 +303,7 @@ sub get_filename {
 		else {
 			$filename = $$config{'filename'};
 			my $padded_index = "";
-			if (exists $$config{'id'}) {
+			if (exists $$config{'id'} && $$config{'id'} ne "") {
 				$padded_index = sprintf("%04d", $$config{'id'});
 			}
 			$filename =~ s/\[id\]/$padded_index/;