The comment says it is done only for the short format: https://github.com/rust-lang/backtrace-rs/blob/57c75298115cf36505725281b4f45f03dacfa290/src/capture.rs#L493-L496 Which matches the printing code in libstd. The actual code however does it for the full format: https://github.com/rust-lang/backtrace-rs/blob/57c75298115cf36505725281b4f45f03dacfa290/src/capture.rs#L501-L507