rustc 2016-04-24 breaks compilation chain

[JohanLorenzo]

Detected by optional travis jobs against nightly. Aster can't compile anymore.

• last passing: b5ba5923f 2016-04-21
• first broken: 645dd013a 2016-04-24

[julienw]

Bug for aster: serde-deprecated/aster#76
Quasi seems to fail as well, there s no bug there (except an old one that is likely obsolete)

[JohanLorenzo]

As @fabricedesre said on IRC, it would be good to include rust-lang/rust#33226 in the next rust up. As of today, the latest version (2016-04-26) doesn't include it.

[JohanLorenzo]

Closed by #465