Auto merge of #3996 - alexcrichton:rustup-up, r=alexcrichton
authorbors <bors@rust-lang.org>
Sat, 6 May 2017 05:04:53 +0000 (05:04 +0000)
committerbors <bors@rust-lang.org>
Sat, 6 May 2017 05:04:53 +0000 (05:04 +0000)
Upgrade rustup used on AppVeyor


Trivial merge