Issue 1:
This is really a bad thing for packages that are intended to be installed globally, and can be a security issue. It isn't in this case because this build was done inside a container + chroot and the RPATH is a directory in / that won't exist.

rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/bin/rust')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/bin/rustc')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/bin/rusti')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/bin/rustdoc')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/bin/rustpkg')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/libstd-4782a756585a81-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/librustc-c84825241471686d-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/libcore-c3ca5d77d81b46c1-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/librusti-5047c7f210c7cac8-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/librust-39583f72884834e3-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/libsyntax-84efebcb12c867a2-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage2/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/rustc/x86_64-unknown-linux-gnu/lib/libstd-4782a756585a81-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage2/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/rustc/x86_64-unknown-linux-gnu/lib/librustc-c84825241471686d-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage2/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/rustc/x86_64-unknown-linux-gnu/lib/libcore-c3ca5d77d81b46c1-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage2/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/rustc/x86_64-unknown-linux-gnu/lib/librusti-5047c7f210c7cac8-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage2/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/rustc/x86_64-unknown-linux-gnu/lib/librust-39583f72884834e3-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage2/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/rustc/x86_64-unknown-linux-gnu/lib/librustdoc-1ac3c0763957e4b0-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage2/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/rustc/x86_64-unknown-linux-gnu/lib/libsyntax-84efebcb12c867a2-0.6.so')
rust E: Insecure RPATH '/build/src/rust-0.6/x86_64-unknown-linux-gnu/stage2/lib/rustc/x86_64-unknown-linux-gnu/lib' in file ('usr/lib/rustc/x86_64-unknown-linux-gnu/lib/librustpkg-795073e423d025b-0.6.so')

For reference: http://wiki.debian.org/RpathIssue

Issue 2:
This should compile but no longer does:

use std::cell::RefCell;

trait Foo {
fn foo(&self) {}
}

impl<T> Foo for T where T: Clone {}

struct Bar;

impl Bar {
fn foo(&self) {}
}

fn main() {
let b = RefCell::new(Bar);
b.borrow().foo()
}

test.rs:17:5: 17:21 error: the trait `core::clone::Clone` is not implemented for the type `core::cell::Ref<'_,Bar>`
test.rs:17 b.borrow().foo()
^~~~~~~~~~~~~~~~

Note that calling Bar.foo() directly works.