Compile tests don't work, unless target directory is sufficiently clean

[hannobraun]

If you're running cargo test before cargo test --features compiletest, you're going to see errors about multiple matching crates. The workaround is to run cargo clean before any call to cargo test --features compiletest.

Full details: Manishearth/compiletest-rs#114

Any help addressing the upstream issue would be highly appreciated. I'm unfamiliar with Cargo and compiletest, and don't have the time to get into it right now.

[hannobraun]

This is not longer an issue, as we're using Trybuild now.