Using absolute paths from std combined with no_implicit_prelude has no edition 2018 compat warning

[Nemo157]

This code compiles without warning on edition 2015 with #![warn(rust_2018_compatibility)] active, but fails to build on edition 2018 (playground):

#![no_implicit_prelude]

#![warn(rust_2018_compatibility)]

fn main() {
    std::process::exit(0);
}

error:

error[E0433]: failed to resolve: use of undeclared type or module `std`
 --> src/main.rs:6:5
  |
6 |     std::process::exit(0);
  |     ^^^ use of undeclared type or module `std`

Note: changing the path to instead use ::std::process::exit compiles on both editions.