Refine complex_graph regex_matches partial suppressions

This updates the comment about GitoxideLabs#1622, including by adding links to
Git mailing list posts by Aarni Koskela, who discovered the bug
that turns out to be the cause of this, and Patrick Steinhardt, who
analyzed the bug and wrote a fix (currently in testing), as well as
GitoxideLabs#1622 (comment),
which summarizes that and reports on its connection to GitoxideLabs#1622.

This also narrows partial suppression of the failing test code
(which consists of conditionally using `parse_spec_no_baseline`
instead of `parse_spec` in some assertions) so that it is only done
if Git is at one of the versions that is known to be affected.

If any future Git versions are affected, such as by the currently
cooking patch not being merged as soon as I expect, then this could
potentially fail on CI again. But that is something we would
probably want to find out about.

Author: EliahKagan

gix/tests/gix/revision/spec/from_bytes/regex.rs

@@ -58,6 +58,7 @@ mod with_known_revision {
 
 mod find_youngest_matching_commit {
     use gix::revision::Spec;
+    use std::borrow::Borrow;
 
     use super::*;
     use crate::revision::spec::from_bytes::parse_spec;
@@ -95,11 +96,19 @@ mod find_youngest_matching_commit {
     fn regex_matches() {
         let repo = repo("complex_graph").unwrap();
 
-        // On the full linux CI `test` workflow, archived baseline aren't used - instead fixtures will be re-evaluated.
-        // As of Git 2.47, its behaviour changed which makes the following assertion fail.
-        // We decided to just ignore it until it's clear that this isn't a bug - obviously the traversal order changed.
-        let is_in_test_ci_workflow = is_ci::cached() && std::env::var_os("GIX_TEST_IGNORE_ARCHIVES").is_some();
-        if is_in_test_ci_workflow {
+        // The full Linux CI `test` job regenerates baselines instead of taking them from archives.
+        // In Git 2.47.0 (and 2.47.1), the traversal order differs, so some `parse_spec` assertions
+        // fail. This is a Git bug with a forthcoming fix. For now, we use `parse_spec_no_baseline`
+        // for them when tests are run that way with known-affected Git versions. For details, see:
+        //
+        //  - https://lore.kernel.org/git/[email protected]/T/
+        //  - https://lore.kernel.org/git/[email protected]/T/
+        //  - https://github.com/GitoxideLabs/gitoxide/issues/1622#issuecomment-2529580735
+        let skip_some_baselines = is_ci::cached()
+            && std::env::var_os("GIX_TEST_IGNORE_ARCHIVES").is_some()
+            && ((2, 47, 0)..(2, 47, 2)).contains(gix_testtools::GIT_VERSION.borrow());
+
+        if skip_some_baselines {
             assert_eq!(
                 parse_spec_no_baseline(":/mes.age", &repo).unwrap(),
                 Spec::from_id(hex_to_id("ef80b4b77b167f326351c93284dc0eb00dd54ff4").attach(&repo))
@@ -116,7 +125,7 @@ mod find_youngest_matching_commit {
             "None of 10 commits reached from all references matched regex \"not there\""
         );
 
-        if is_in_test_ci_workflow {
+        if skip_some_baselines {
             assert_eq!(
                 parse_spec_no_baseline(":/!-message", &repo).unwrap(),
                 Spec::from_id(hex_to_id("55e825ebe8fd2ff78cad3826afb696b96b576a7e").attach(&repo))