Auto merge of #5540 - ehuss:fix-build-plan-tests, r=alexcrichton
authorbors <bors@rust-lang.org>
Tue, 15 May 2018 14:55:06 +0000 (14:55 +0000)
committerbors <bors@rust-lang.org>
Tue, 15 May 2018 14:55:06 +0000 (14:55 +0000)
Fix tests when CARGO_TARGET_DIR is set.

Fixes #5536


Trivial merge