Merge branch 'rustup' of https://github.com/globin/cargo into rustup

diff --cc src/cargo/ops/cargo_rustc/context.rs
Simple merge

diff --cc src/cargo/util/errors.rs
index a13e7410f4bb2284084d6f7312d548a73440d1bc,6e368712e6ffb56e20e5355406a3b1b11f6b04ae..712c1a3604ab39d394966de1b2d6b23b4073769b
--- 1/src/cargo/util/errors.rs
--- 2/src/cargo/util/errors.rs
+++ b/src/cargo/util/errors.rs
@@@ -70,18 -71,8 +71,18 @@@ impl<T, E: CargoError + 'static> ChainE
      }
  }
  
 +impl<T> ChainError<T> for Box<CargoError> {
 +    fn chain_error<E2, C>(self, callback: C) -> CargoResult<T>
 +                         where E2: CargoError, C: FnOnce() -> E2 {
 +        Err(Box::new(ChainedError {
 +            error: callback(),
 +            cause: self,
 +        }) as Box<CargoError>)
 +    }
 +}
 +
  impl<T> ChainError<T> for Option<T> {
-     fn chain_error<E, C>(self, callback: C) -> CargoResult<T>
+     fn chain_error<E: 'static, C>(self, callback: C) -> CargoResult<T>
                           where E: CargoError, C: FnOnce() -> E {
          match self {
              Some(t) => Ok(t),