Auto merge of #4201 - alexcrichton:more-human, r=matklad
authorbors <bors@rust-lang.org>
Wed, 21 Jun 2017 18:26:14 +0000 (18:26 +0000)
committerbors <bors@rust-lang.org>
Wed, 21 Jun 2017 18:26:14 +0000 (18:26 +0000)
Flag crate registry errors as "human"

They often contain useful information!

Closes #4200


Trivial merge