Rust update: no more `[T, ..n]` -> `&[T]` coercion
Rust update: no more `[T, ..n]` -> `&[T]` coercion

(Missed one in the doc tests)

servo/rust-http,chris-morgan/rust-http,Shraddha512/rust-http,Shraddha512/rust-http,Shraddha512/rust-http,chris-morgan/rust-http,Shraddha512/rust-http,servo/rust-http,servo/rust-http,chris-morgan/rust-http,chris-morgan/rust-http,servo/rust-http,Shraddha512/rust-http