Fix kernel_require.rb packed at wrong path when rubygems-update is installed

When rubygems-update is installed (e.g. via asdf on Linux/macOS), rubygems.rb
lives in site_ruby rather than rubylibdir. Since rubygems.rb uses require_relative
to load kernel_require.rb, both files must reside in the same directory tree.

Previously kernel_require.rb was always located from rubylibdir, causing a
path mismatch at runtime: rubygems.rb in site_ruby could not find kernel_require.rb.

Fix by preferring the directory of the actually-loaded rubygems.rb from
$LOADED_FEATURES, falling back to rubylibdir for standard Ruby installations
(including RubyInstaller on Windows).

Author: Largo

lib/ocran/direction.rb

@@ -100,12 +100,25 @@ def normalized_features
       # Since https://github.com/rubygems/rubygems/commit/cad4cf16cf8fcc637d9da643ef97cf0be2ed63cb
       # rubygems/core_ext/kernel_require.rb is loaded via IO.read+eval rather than require,
       # so it never appears in $LOADED_FEATURES and must be added manually.
-      # Use RbConfig::CONFIG["rubylibdir"] directly so the path is always correct,
-      # regardless of Ruby version or platform path separator conventions.
+      # We check multiple candidate locations because the layout varies by Ruby setup:
+      # - Standard Ruby (including RubyInstaller on Windows): rubygems.rb lives in rubylibdir
+      # - Ruby with rubygems-update (e.g. asdf on Linux/macOS): rubygems.rb lives in site_ruby
+      # kernel_require.rb must be packed alongside the rubygems.rb that was actually loaded,
+      # because rubygems.rb uses require_relative to load it.
       kernel_require_rel = "rubygems/core_ext/kernel_require.rb"
       unless features.any? { |f| f.to_posix.end_with?(kernel_require_rel) }
-        kernel_require_path = Pathname(RbConfig::CONFIG["rubylibdir"]) / kernel_require_rel
-        features.push(kernel_require_path) if kernel_require_path.exist?
+        # Prefer the location alongside the actually-loaded rubygems.rb, fall back to rubylibdir
+        rubygems_feature = features.find { |f| f.to_posix.end_with?("/rubygems.rb") }
+        candidate_dirs = []
+        candidate_dirs << rubygems_feature.dirname if rubygems_feature
+        candidate_dirs << Pathname(RbConfig::CONFIG["rubylibdir"])
+        candidate_dirs.each do |base_dir|
+          kernel_require_path = base_dir / kernel_require_rel
+          if kernel_require_path.exist?
+            features.push(kernel_require_path)
+            break
+          end
+        end
       end
 
       # Convert all relative paths to absolute paths before building.

test/test_ocra.rb

@@ -1077,7 +1077,6 @@ def test_glimmer_libui
   # zlib1.dll in archdir. Without them the SxS activation context fails with
   # error 14001 at runtime. Verifies that compress/decompress round-trips work.
   def test_zlib
-    skip "SxS manifest test is Windows-only" unless Gem.win_platform?
     with_fixture 'zlib' do
       assert system("ruby", ocran, "zlib.rb", *DefaultArgs)
       assert File.exist?(exe_name("zlib"))