Auto merge of rust-lang#49518 - SimonSapin:prelude, r=alexcrichton

Revert "Add TryFrom and TryInto to the prelude"

This reverts commit 09008cc.

This addition landed in rust-lang#49305 and turned out to break crates that had their own copy of `TryFrom` in order to use it on the Stable channel :(

We’ll explore the possibility of the 2018 edition having a different prelude that includes this traits. However per the editions RFC this requires implementing a warning in the 2015 edition for code that *would* break.

Author: bors

src/libcore/prelude/v1.rs

@@ -39,9 +39,6 @@ pub use cmp::{PartialEq, PartialOrd, Eq, Ord};
 #[stable(feature = "core_prelude", since = "1.4.0")]
 #[doc(no_inline)]
 pub use convert::{AsRef, AsMut, Into, From};
-#[stable(feature = "try_from", since = "1.26.0")]
-#[doc(no_inline)]
-pub use convert::{TryFrom, TryInto};
 #[stable(feature = "core_prelude", since = "1.4.0")]
 #[doc(no_inline)]
 pub use default::Default;

src/libstd/prelude/v1.rs

@@ -35,8 +35,6 @@
 #[doc(no_inline)] pub use cmp::{PartialEq, PartialOrd, Eq, Ord};
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)] pub use convert::{AsRef, AsMut, Into, From};
-#[stable(feature = "try_from", since = "1.26.0")]
-#[doc(no_inline)] pub use convert::{TryFrom, TryInto};
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)] pub use default::Default;
 #[stable(feature = "rust1", since = "1.0.0")]