This was fixed in pulldown_cmark 0.7.1, specifically https://github.com/raphlinus/pulldown-cmark/pull/438
// run-pass
compiletest UI tests do not fail when encountering panics and ICEs unless the `// run-pass` flag is used. (This was forgotten in https://github.com/rust-lang/rust-clippy/pull/3743)
This should give us more UI coverage for free. It also removes the `run-pass` suite, so we now only have the `ui` suite.