Add DUP_TOOLS as supported arg0
Add DUP_TOOLS as supported arg0

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