Update toolchain used to build rustup

Author: brson

.travis.yml

@@ -76,7 +76,7 @@ install:
   - sudo pip install awscli
   - aws configure set preview.cloudfront true
   - curl https://static.rust-lang.org/rustup.sh |
-    sh -s -- --prefix=$HOME/rust --spec=nightly-2016-08-10 --with-target=$TARGET
+    sh -s -- --prefix=$HOME/rust --spec=nightly-2016-09-29 --with-target=$TARGET
 
 script:
   - mkdir target

appveyor.yml

@@ -22,7 +22,7 @@ install:
   # Install rust, x86_64-pc-windows-msvc host
   # FIXME: switch back to win.rustup.rs
   - curl -sSf -o rustup-init.exe https://dev-static.rust-lang.org/rustup/dist/i686-pc-windows-gnu/rustup-init.exe
-  - rustup-init.exe -y --default-toolchain=nightly-2016-08-10-x86_64-pc-windows-msvc
+  - rustup-init.exe -y --default-toolchain=nightly-2016-09-29-x86_64-pc-windows-msvc
   - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
 
   # Install the target we're compiling for