message: Fix test not to rely on `cargo` in PATH.
diff: @@ -1719,7 +1719,7 @@ fn fix_with_run_cargo_in_proc_macros() {
  #[proc_macro]
  pub fn foo(_input: TokenStream) -> TokenStream {
  - let output = std::process::Command::new("cargo")
  + let output = std::process::Command::new(env!("CARGO"))
  .args(&["metadata", "--format-version=1"])
  .output()
  .unwrap();
  