I landed a rustup in https://github.com/fxbox/foxbox/commit/4ada64533658fdee4f2bc35ad9bf0f439bc1999d that moves us to rustc from 2016-04-29
Time to update your tools!
And… update again, now to Rustc 2016-05-07
Current version is now 2016-05-07
You likely wanted to say Current version is 2016-05-22 
Yep, thanks Oleg!
Hopefully getting it right today: we are now using 2016-05-29
And thanks to a clippy change, we’re now on 2016-05-31
Now on 2016-06-16 because of an Aster update.
and now on nightly-2016-06-24 for the same reason.