[rubygems/rubygems] Ensure refs directory in cached git source

See https://github.com/rubygems/rubygems/issues/8046 for details

Prior to this commit a cached git source without a specific ref wouldn't
survive pushing to a remote and then pulling on a different machine.
We'd end up without a refs directory in the cache, at which point git
won't recognize it as a repo.

This commit fixes the problem by adding a refs directory if it's not
already there. This needs to be done as early as possible, so any git
commands will work as expected, so this commit adds it before creating
the app cached git proxy.

8c89f0b065

lib/bundler/source/git.rb

@@ -188,7 +188,7 @@ module Bundler
       end
 
       def specs(*)
-        set_cache_path!(app_cache_path) if use_app_cache?
+        set_up_app_cache!(app_cache_path) if use_app_cache?
 
         if requires_checkout? && !@copied
           FileUtils.rm_rf(app_cache_path) if use_app_cache? && git_proxy.not_a_bare_repository?
@@ -320,6 +320,11 @@ module Bundler
         @install_path = path
       end
 
+      def set_up_app_cache!(path)
+        FileUtils.mkdir_p(path.join("refs"))
+        set_cache_path!(path)
+      end
+
       def has_app_cache?
         cached_revision && super
       end

spec/bundler/cache/git_spec.rb

@@ -212,6 +212,34 @@ RSpec.describe "bundle cache with git" do
     expect(the_bundle).to include_gem "foo 1.0"
   end
 
+  it "can install after bundle cache without cloning remote repositories with only git tracked files" do
+    build_git "foo"
+
+    gemfile <<-G
+      source "https://gem.repo1"
+      gem "foo", :git => '#{lib_path("foo-1.0")}'
+    G
+    bundle "config set cache_all true"
+    bundle :cache, "all-platforms" => true
+    FileUtils.rm_rf Dir.glob(default_bundle_path("bundler/gems/extensions/**/foo-1.0-*")).first.to_s
+    FileUtils.rm_rf Dir.glob(default_bundle_path("bundler/gems/foo-1.0-*")).first.to_s
+
+    simulate_new_machine
+    bundle "config set frozen true"
+    FileUtils.rm_rf "#{default_bundle_path}/cache/bundler/git/foo-1.0-*"
+
+    # Remove untracked files (including the empty refs dir in the cache)
+    Dir.chdir(bundled_app) do
+      system(*%W[git init --quiet])
+      system(*%W[git add --all])
+      system(*%W[git clean -d --force --quiet])
+    end
+
+    bundle "install --local --verbose"
+    expect(out).to_not include("Fetching")
+    expect(the_bundle).to include_gem "foo 1.0"
+  end
+
   it "copies repository to vendor cache" do
     # CVE-2022-39253: https://lore.kernel.org/lkml/xmqq4jw1uku5.fsf@gitster.g/
     system(*%W[git config --global protocol.file.allow always])