fix: replacing default RUST_LOG environement variable with starship specific one, to prevent interlacing (starship#1280)

Co-authored-by: Kappitou Anouar <[email protected]>

Author: anouarkappitou

CONTRIBUTING.md

@@ -27,15 +27,15 @@ Any styling that is applied to a module is inherited by its segments. Module pre
 ## Logging
 
 Debug logging in starship is done with [pretty_env_logger](https://crates.io/crates/pretty_env_logger).
-To run starship with debug logs, set the `RUST_LOG` environment variable to the log level needed.
+To run starship with debug logs, set the `STARSHIP_LOG` environment variable to the log level needed.
 For example, to enable the trace logs, run the following:
 
 ```sh
 # Run installed starship
-RUST_LOG=starship=trace starship
+STARSHIP_LOG=starship=trace starship
 
 # Run with cargo
-RUST_LOG=starship=trace cargo run
+STARSHIP_LOG=starship=trace cargo run
 ```
 
 ## Linting
@@ -118,4 +118,4 @@ This is our preferred process for opening a PR on GitHub:
 4. When your changes are ready for review, push your branch: `git push origin my-feature-branch`
 5. Create a pull request from your branch to `starship/master`
 6. No need to assign the pull request to anyone, we'll review it when we can
-7. When the changes have been reviewed and approved, someone will squash and merge for you
+7. When the changes have been reviewed and approved, someone will squash and merge for you

src/main.rs

@@ -23,7 +23,7 @@ use crate::module::ALL_MODULES;
 use clap::{App, AppSettings, Arg, Shell, SubCommand};
 
 fn main() {
-    pretty_env_logger::init();
+    pretty_env_logger::init_custom_env("STARSHIP_LOG");
 
     let status_code_arg = Arg::with_name("status_code")
         .short("s")