Change:
The bots are currently failing like so I bisected to , which changes how works.
Closing since I'm almost certain that test is either gone, or passes.
This continues to be a source of breakage on incoming. Right now the failure is in rpass/auto-encode
run-pass/auto-encode is xfailed now
my branch contains a reduced test case under run-pass/issue-6122
incoming has been poofed, so I'm not sure what the status of this is. Bors has been churning away and the tree is green, so does the problem still arise?
The test passes locally for me with some updating. Pushed it to try, will see how it falls.

Discussion:
// xfail-fast <del> // Copyright 2012 The Rust Project Developers. See the COPYRIGHT </del> <ins> // Copyright 2013 The Rust Project Developers. See the COPYRIGHT </ins> // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. //

// option. This file may not be copied, modified, or distributed // except according to those terms. <del> // xfail-test #6122 </del> <ins> #[feature(managed_boxes)]; </ins> extern mod extra;

// the common code. use std::hashmap::{HashMap, HashSet}; <ins> use std::io::Decorator; </ins> use EBReader = extra::ebml::reader; use EBWriter = extra::ebml::writer;

Encodable<EBWriter::Encoder> + Decodable<EBReader::Decoder> >(a1: &A) { <del> let bytes = do io::with_bytes_writer |wr| { let mut ebml_w = EBWriter::Encoder(wr); a1.encode(&mut ebml_w) }; </del> <ins> let mut wr = @mut std::io::mem::MemWriter::new(); let mut ebml_w = EBWriter::Encoder(wr); a1.encode(&mut ebml_w); let bytes = wr.inner_ref().to_owned(); </ins> let d = EBReader::Doc(@bytes); let mut decoder = EBReader::Decoder(d); let a2: A = Decodable::decode(&mut decoder); <del> if !(*a1 == a2) { ::std::sys::FailWithCause::fail_with(~"explicit failure" + "foo", "auto-encode.rs", 43u); } </del> assert!(*a1 == a2); }

let a = &Plus(@Minus(@Val(3u), @Val(10u)), @Plus(@Val(22u), @Val(5u))); test_ebml(a); <del> //    let a = &Spanned {lo: 0u, hi: 5u, node: 22u}; //    test_ebml(a); </del> <ins> let a = &Spanned {lo: 0u, hi: 5u, node: 22u}; test_ebml(a); </ins> <del> //    let a = &Point {x: 3u, y: 5u}; //    test_ebml(a); // //    let a = &@[1u, 2u, 3u]; //    test_ebml(a); // //    let a = &Top(22u); //    test_ebml(a); // //    let a = &Bottom(222u); //    test_ebml(a); // //    let a = &A; //    test_ebml(a); // //    let a = &B; //    test_ebml(a); </del> <ins> let a = &Point {x: 3u, y: 5u}; test_ebml(a); let a = &@[1u, 2u, 3u]; test_ebml(a); let a = &Top(22u); test_ebml(a); let a = &Bottom(222u); test_ebml(a); let a = &A; test_ebml(a); let a = &B; test_ebml(a); </ins> <del> println("Hi1"); </del> let a = &time::now(); test_ebml(a); <del> println("Hi2"); //    test_ebml(&1.0f32); //    test_ebml(&1.0f64); test_ebml(&1.0f); //    println("Hi3"); //    test_ebml(&'a'); </del> <ins> test_ebml(&1.0f32); test_ebml(&1.0f64); test_ebml(&'a'); </ins> <del> println("Hi4"); </del> let mut a = HashMap::new(); test_ebml(&a); a.insert(1, 2); <del> println("Hi4"); </del> test_ebml(&a); <del> //    let mut a = HashSet::new(); //    test_ebml(&a); //    a.insert(1); //    test_ebml(&a); </del> <ins> let mut a = HashSet::new(); test_ebml(&a); a.insert(1); test_ebml(&a); </ins> }