message: Remove likely brittle test.
  This is too dependent on the particulars of libstd.
diff: @@ -211,59 +211,3 @@ fn custom_test_framework() {
  .build_std_arg("core")
  .run();
  }
  -
  -#[cargo_test(build_std)]
  -fn common_crate_collision() {
  - // Check for collision with `cc` crate in build dependencies.
  - // This needs to be a full test since we need to use the real `cc` crate.
  - // This is a bit fragile, since it assumes `cc` is used in libstd,
  - // and that we are selecting the same features.
  -
  - // Determine the version of CC used in the real std so that we use the
  - // exact same version.
  - let sysroot = paths::sysroot();
  - let sysroot = Path::new(&sysroot);
  - let contents =
  - std::fs::read_to_string(sysroot.join("lib/rustlib/src/rust/Cargo.lock")).unwrap();
  - let lock: toml::Value = toml::from_str(&contents).unwrap();
  - let mut packages = lock["package"].as_array().unwrap().iter();
  - let cc = packages
  - .find(|p| p["name"].as_str().unwrap() == "cc")
  - .unwrap();
  - // Make sure there is only one `cc`.
  - assert!(packages
  - .find(|p| p["name"].as_str().unwrap() == "cc")
  - .is_none());
  - let cc_version = cc["version"].as_str().unwrap();
  -
  - let p = project()
  - .file(
  - "Cargo.toml",
  - &format!(
  - r#"
  - [package]
  - name = "foo"
  - version = "0.1.0"
  -
  - [build-dependencies]
  - cc = "={}"
  - "#,
  - cc_version
  - ),
  - )
  - .file("build.rs", "extern crate cc; fn main() {}")
  - .file("src/main.rs", "fn main() {}")
  - .build();
  -
  - p.cargo("build -v")
  - .build_std()
  - .target_host()
  - .with_stderr_contains(
  - "[RUNNING] `rustc --crate-name cc [..]-Zforce-unstable-if-unmarked[..]",
  - )
  - .with_stderr_line_without(
  - &["[RUNNING] `rustc --crate-name cc"],
  - &["-Zforce-unstable-if-unmarked"],
  - )
  - .run();
  -}
  