Refresh branch cache after `git gc`

Possible workaround for #15392

CHANGELOG

@@ -4,7 +4,7 @@ v 8.10.0 (unreleased)
   - Expose {should,force}_remove_source_branch (Ben Boeckel)
   - Fix commit builds API, return all builds for all pipelines for given commit. !4849
   - Replace Haml with Hamlit to make view rendering faster. !3666
-  - Expire the branch cache after `git gc` runs
+  - Refresh the branch cache after `git gc` runs
   - Refactor repository paths handling to allow multiple git mount points
   - Optimize system note visibility checking by memoizing the visible reference count !5070
   - Add Application Setting to configure default Repository Path for new projects

app/workers/git_garbage_collect_worker.rb

@@ -8,7 +8,9 @@ class GitGarbageCollectWorker
     project = Project.find(project_id)
 
     gitlab_shell.gc(project.repository_storage_path, project.path_with_namespace)
-    # Expire the branch cache in case garbage collection caused a ref lookup to fail
+    # Refresh the branch cache in case garbage collection caused a ref lookup to fail
     project.repository.after_create_branch
+    project.repository.branch_names
+    project.repository.has_visible_content?
   end
 end

spec/workers/git_garbage_collect_worker_spec.rb

@@ -16,7 +16,10 @@ describe GitGarbageCollectWorker do
         project.repository_storage_path,
         project.path_with_namespace).
       and_return(true)
-      expect_any_instance_of(Repository).to receive(:after_create_branch)
+      expect_any_instance_of(Repository).to receive(:after_create_branch).and_call_original
+      expect_any_instance_of(Repository).to receive(:branch_names).and_call_original
+      expect_any_instance_of(Repository).to receive(:branch_count).and_call_original
+      expect_any_instance_of(Repository).to receive(:has_visible_content?).and_call_original
 
       subject.perform(project.id)
     end