Auto merge of #3146 - alexcrichton:install-same-workspace, r=brson
authorbors <bors@rust-lang.org>
Thu, 6 Oct 2016 04:33:12 +0000 (21:33 -0700)
committerGitHub <noreply@github.com>
Thu, 6 Oct 2016 04:33:12 +0000 (21:33 -0700)
Use workspaces during `cargo install`

Prevent lock files from oscillating.

Closes #3133


Trivial merge