Multiple associated type bindings cause problems

[nikomatsakis]

This test doesn't pass:

// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![feature(associated_types)]

trait Foo {
    type X;
    type Y;
}

fn foo<T:Foo<X=int,Y=int>>(t: &T)
{
    bar(t);
    baz(t);
}
fn bar<T:Foo<X=int>>(t: &T) { }
fn baz<T:Foo<Y=int>>(t: &T) { }

fn main() { }

[nikomatsakis]

Can also manifest as an ICE:

// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![feature(associated_types)]

trait Foo {
    type X;
    type Y;
}

fn foo<T:Foo<X=int>>(t: &T)
{
    baz(t);
}
fn baz<T:Foo<Y=int>>(t: &T) { }

fn main() { }

reports:

thread 'rustc' panicked at 'assertion failed: `(left == right) && (right == left)` (left: `"X"(62)`,
right: `"Y"(63)`)', /home/nmatsakis/versioned/rust-3/src/librustc/middle/traits/project.rs:599

[apasel422]

Is #20521 at all related to this?