Lots of [discussion](https://internals.rust-lang.org/t/stage1-tests-and-landing-pads/2606/10) as well as [proposed](https://github.com/rust-lang/rust/pull/28206/files) [fixes](https://github.com/rust-lang/rust/pull/27417). Looks like the best solution for now (from the discuss thread) is to just enable landing pads in all stages instead of just disabling in stage0.