Auto merge of #5333 - dwijnand:warn-install-2018, r=matklad
authorbors <bors@rust-lang.org>
Wed, 11 Apr 2018 05:04:28 +0000 (05:04 +0000)
committerbors <bors@rust-lang.org>
Wed, 11 Apr 2018 05:04:28 +0000 (05:04 +0000)
Warn/error when cargo installing the cwd in 2015/2018

Fixes #5327

submitted for early review. feedback very welcome, I'm happy to iterate (and learn).


Trivial merge