Auto merge of #4579 - mdevlamynck:issue-3388, r=alexcrichton
authorbors <bors@rust-lang.org>
Wed, 4 Oct 2017 22:04:49 +0000 (22:04 +0000)
committerbors <bors@rust-lang.org>
Wed, 4 Oct 2017 22:04:49 +0000 (22:04 +0000)
Fix error message when Cargo.toml misses a [package] section

Fixes #3388.


Trivial merge