Auto merge of #5503 - ehuss:fix-rustc-test, r=matklad
authorbors <bors@rust-lang.org>
Thu, 10 May 2018 12:44:16 +0000 (12:44 +0000)
committerbors <bors@rust-lang.org>
Thu, 10 May 2018 12:44:16 +0000 (12:44 +0000)
Fix `cargo rustc` for test with implicit binary.

Fixes #5502


Trivial merge