Unreachable expression warnings with panics

[tvallotton]

The todo!() macro produces an unreachable expression warning:

#[throws(Error)]
fn foo() {
    todo!()
}

warning: unreachable expression
 --> rocket_lang/src/main.rs:4:1
  |
4 | #[throws(Error)]
  | ^^^^^^^^^^^^^^^^ unreachable expression
5 | fn foo() {
6 |     todo!()
  |     ------- any code following this expression is unreachable
  |
  = note: `#[warn(unreachable_code)]` on by default
  = note: this warning originates in the attribute macro `throws` (in Nightly builds, run with -Z macro-backtrace for more info)

It'd be nice if this were be fixed if possible.

[Nemo157]

This is actually fixed in master, by df2e3d4