Unboxed closures ICE when debug println!()d

[tiffany352]

error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'couldn't find visit method for err', /build/rust-git/src/rust/src/libcore/option.rs:243

Test case:

#![feature(unboxed_closures, unboxed_closure_sugar)]

extern crate debug;

fn main() {
    let foo = |: x: int| x+1;
    println!("{:?}", foo);
}

Playpen link: http://is.gd/9i2oSm

[bkoropoff]

This was actually fixed, and now debug formatting has been completely removed anyway.