message: Make rust-docs component optional for local testing.
diff: //! Tests for the -Zrustdoc-map feature.
  use cargo_test_support::registry::Package;
  -use cargo_test_support::{is_nightly, project, Project};
  +use cargo_test_support::{is_nightly, paths, project, Project};
  fn basic_project() -> Project {
  Package::new("bar", "1.0.0")
  @@ -78,6 +78,18 @@ fn std_docs() {
  // --extern-html-root-url is unstable
  return;
  }
  + if !cargo::util::is_ci() {
  + // For local developers, skip this test if docs aren't installed.
  + let docs = std::path::Path::new(&paths::sysroot()).join("share/doc/rust/html");
  + if !docs.exists() {
  + eprintln!(
  + "documentation not found at {}, \
  + skipping test (run `rustdoc component add rust-docs` to install",
  + docs.display()
  + );
  + return;
  + }
  + }
  let p = basic_project();
  p.change_file(
  ".cargo/config",
  