Function list_line 

fn list_line(label: &str, items: &[String], cap: usize) -> String

A list line: everything when it fits, and when it does not, the first entry plus the newest cap - 1 with the omission stated.

The first is kept on purpose. The file a successor first changed, or the command that started the work, is usually the one it will need again; a newest-only cut loses exactly that one.