This fixes a bug in insert_history_lines where writing `Line::From(vec!["A".bold(), "B".into()])` would write "B" as bold, because "B" didn't explicitly subtract bold.
This fixes a bug in insert_history_lines where writing `Line::From(vec!["A".bold(), "B".into()])` would write "B" as bold, because "B" didn't explicitly subtract bold.