message: Bring test of nightly in line with tests
diff: @@ -88,8 +88,10 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
  // ignore CARGO_INCREMENTAL on anything but nightly. This allows users
  // to always have CARGO_INCREMENTAL set without getting unexpected
  // errors on stable/beta builds.
  - let incremental_enabled = incremental_enabled
  - && config.rustc()?.verbose_version.contains("nightly");
  + let is_nightly =
  + config.rustc()?.verbose_version.contains("-nightly") ||
  + config.rustc()?.verbose_version.contains("-dev");
  + let incremental_enabled = incremental_enabled && is_nightly;
  Ok(Context {
  ws: ws,
  