Auto merge of #3485 - sfackler:useragent, r=alexcrichton
authorbors <bors@rust-lang.org>
Mon, 2 Jan 2017 18:09:26 +0000 (18:09 +0000)
committerbors <bors@rust-lang.org>
Mon, 2 Jan 2017 18:09:26 +0000 (18:09 +0000)
Set a user agent with the version when talking to the registry

This can be used to track what versions of Cargo are being used in the
wild, which can be very useful.

r? @alexcrichton


Trivial merge