pattern confusion

gistfile1.txt

fn is_file(path: &str) -> bool {
   let p = Path::new(path);
   match io::result(|| std::io::fs::stat(&p)) {
      Ok(stat) => {
         match stat.kind {
            TypeFile => { return true; }
            _ => { return false; }
         }
      }
      Err(e)   => { return false; }
   }
}

gistfile2.txt

rustc -o ./bin/testloop-rs --bin --opt-level=0 src/testloop-rs.rs
src/testloop-rs.rs:61:12: 61:13 error: unreachable pattern
src/testloop-rs.rs:61             _ => { return false; }
                                  ^
error: aborting due to previous error