Auto merge of #245 - servo:travis-bump, r=jdm
Auto merge of #245 - servo:travis-bump, r=jdm

Update nightly Rust version to keep in sync with Servo.

Rustup happened in https://github.com/servo/servo/pull/10076/

servo/webrender,alanamramjit/webrender,servo/webrender,servo/webrender,alanamramjit/webrender,servo/webrender,servo/webrender,servo/webrender