Add idempotent PATH update shell script
Add idempotent PATH update shell script

nodakai/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,rust-lang/rustup,nodakai/rustup.rs,rust-lang/rustup,rust-lang/rustup,nodakai/rustup.rs