message: Fix panic-in-panic in tests.
  There are some very rare circumstances that can cause a double panic during
  development. For example, `.with_json("")` will panic, and then the drop
  will also panic.
diff: @@ -1162,7 +1162,7 @@ impl Execs {
  impl Drop for Execs {
  fn drop(&mut self) {
  - if !self.ran {
  + if !self.ran && !std::thread::panicking() {
  panic!("forgot to run this command");
  }
  }
  