`RUST_BACKTRACE=full cargo version` results in [this](https://gist.github.com/jkcclemens/edafe6e9a22d85ae662108bc5dc7ea35). That backtrace is from macOS 10.12.4 beta. I have verified this issue exists on both macOS and Arch. [Arch backtrace](https://gist.github.com/jkcclemens/f9ba90448d9902054fb73b974591d796).