tests: update version-verbose-commit-hash

- No longer gate by `//@ needs-git-hash`. Instead, check for
  `COMPILETEST_HAS_GIT_HASH=1` env var being set.
- Document the env var and reason for bypassing bootstrap.

Author: jieyouxu

tests/run-make/version-verbose-commit-hash/rmake.rs

@@ -1,20 +1,33 @@
-// `--version --verbose` should display the git-commit hashes of rustc and rustdoc, but this
-// functionality was lost due to #104184. After this feature was returned by #109981, this
-// test ensures it will not be broken again.
-// See https://github.com/rust-lang/rust/issues/107094
-
-//@ needs-git-hash
+//! `--version --verbose` should display the git-commit hashes of rustc and rustdoc, but this
+//! functionality was lost due to #104184. After this feature was returned by #109981, this
+//! test ensures it will not be broken again.
+//! See <https://github.com/rust-lang/rust/issues/107094>.
+//!
+//! # Important note
+//!
+//! This test is **not** gated by compiletest, and **cannot** trust bootstrap's git-hash logic e.g.
+//! if bootstrap reports git-hash is available yet the built rustc doesn't actually have a hash. It
+//! must directly communicate with CI, and gate it being run on an env var expected to be set in CI
+//! (or that env var being set locally), `COMPILETEST_HAS_GIT_HASH=1`.
 
 use run_make_support::{bare_rustc, bare_rustdoc, regex};
 
 fn main() {
+    if !std::env::var("COMPILETEST_HAS_GIT_HASH").is_ok_and(|v| v == "1") {
+        return;
+    }
+
     let out_rustc =
         bare_rustc().arg("--version").arg("--verbose").run().stdout_utf8().to_lowercase();
     let out_rustdoc =
         bare_rustdoc().arg("--version").arg("--verbose").run().stdout_utf8().to_lowercase();
     let re =
         regex::Regex::new(r#"commit-hash: [0-9a-f]{40}\ncommit-date: [0-9]{4}-[0-9]{2}-[0-9]{2}"#)
             .unwrap();
+
+    println!("rustc:\n{}", out_rustc);
+    println!("rustdoc:\n{}", out_rustdoc);
+
     assert!(re.is_match(&out_rustc));
     assert!(re.is_match(&out_rustdoc));
 }