Auto merge of #2920 - alexcrichton:wut, r=brson
authorbors <bors@rust-lang.org>
Wed, 27 Jul 2016 00:20:08 +0000 (17:20 -0700)
committerGitHub <noreply@github.com>
Wed, 27 Jul 2016 00:20:08 +0000 (17:20 -0700)
Improve file open error when packaging crates

Be sure to point to the file in question.

Closes #2914


Trivial merge