Sysroot fails to update when using rustup's rust-src component

[FenrirWolf]

I've been trying out using the rust-src component and encounter the following error whenever I update to a new nightly version of Rust:

xargo build --release
   Compiling ctru-sys v0.2.0 (file:///home/fenrir/projects/ctru-rs/ctru-sys)
   Compiling rust3ds-template v0.1.0 (file:///home/fenrir/projects/rust3ds-template)
   Compiling alloc_system3ds v0.1.0 (https://github.com/rust3ds/alloc_system3ds?rev=da38c94#da38c941)
   Compiling ctru-rs v0.4.0 (file:///home/fenrir/projects/ctru-rs)
error[E0514]: found crate `core` compiled by an incompatible version of rustc
  |
  = help: please recompile that crate using this compiler (rustc 1.13.0-nightly (2c01bb885 2016-08-31))
  = note: crate `core` path #1: /home/fenrir/.xargo/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore-411f48d3.rlib compiled by "rustc 1.13.0-nightly (eac41469d 2016-08-30)"
  = note: crate `core` path #2: /home/fenrir/.xargo/lib/rustlib/3ds/lib/libcore.rlib compiled by "rustc 1.13.0-nightly (eac41469d 2016-08-30)"

error: aborting due to previous error

Deleting the existing sysroot allows it to successfully rebuild, and deleting the rust-src component so that xargo falls back to its old behavior also results in a successful rebuild.

[japaric]

I've released a new version with a fix for this.

Thanks for reporting, @FenrirWolf!