task '<unnamed>' failed at 'explicit failure', /build/rust-git/src/rust/src/libsyntax/diagnostic.rs:101
task '<unnamed>' failed at 'explicit failure', /build/rust-git/src/rust/src/librustc/rustc.rs:395

It's more messy than informative, isn't it?

This might go away when rustc stops unwinding and just aborts, but I wonder whether we oughtn't have some way to suppress those messages, since I imagine a lot of commandliney programs that use unwinding won't want to expose their internal task failures to the console, unless they're tearing down the entire runtime with linked failure.