Auto merge of #3930 - alexcrichton:more-clean, r=alexcrichton
authorbors <bors@rust-lang.org>
Tue, 18 Apr 2017 01:16:05 +0000 (01:16 +0000)
committerbors <bors@rust-lang.org>
Tue, 18 Apr 2017 01:16:05 +0000 (01:16 +0000)
Clean some more env vars during tests

Will be required to run tests as part of rust-lang/rust


Trivial merge