message: we don't need unstable options
diff: @@ -45,8 +45,7 @@ pub fn build_dependencies(config: &Config) -> Result<Dependencies> {
  setup_command(&mut build);
  build
  .arg("--target-dir=target/test_dependencies")
  - .arg("--message-format=json")
  - .arg("-Zunstable-options");
  + .arg("--message-format=json");
  let output = build.output()?;
  