Auto merge of #2940 - matklad:ambiguous-deps, r=alexcrichton
authorbors <bors@rust-lang.org>
Mon, 1 Aug 2016 15:51:40 +0000 (08:51 -0700)
committerGitHub <noreply@github.com>
Mon, 1 Aug 2016 15:51:40 +0000 (08:51 -0700)
Warn about unused keys in dependency specification

Closes #2869 and #2695


Trivial merge