Repos leave object pool when moving to a new shard

When a project's repositories are moved to a new shard, the pool
repository is still located at the old shard. This doesn't work anymore,
as git doesn't have access to that.

The unlink RPC is called as it cleans up the remote. The alternate file
is removed too, which doesn't exist, but this doesn't fail the move.

Fixes: https://gitlab.com/gitlab-org/gitlab-ee/issues/9094

ee/app/services/projects/update_repository_storage_service.rb

@@ -19,6 +19,7 @@ module Projects
         mark_old_paths_for_archive
 
         project.update(repository_storage: new_repository_storage_key, repository_read_only: false)
+        project.leave_pool_repository
         project.track_project_repository
       else
         project.update(repository_read_only: false)

ee/changelogs/unreleased/zj-move-repository-storages-pool-repo.yml

+---
+title: Moving repository across shards leaves the pool
+merge_request:
+author:
+type: added

ee/spec/services/projects/update_repository_storage_service_spec.rb

@@ -46,7 +46,7 @@ describe Projects::UpdateRepositoryStorageService do
       end
     end
 
-    context 'with wiki', :disable_gitaly do
+    context 'with wiki' do
       let(:project) { create(:project, :repository, repository_read_only: true, wiki_enabled: true) }
       let(:repository_double) { double(:repository) }
       let(:wiki_repository_double) { double(:repository) }
@@ -105,5 +105,18 @@ describe Projects::UpdateRepositoryStorageService do
         end
       end
     end
+
+    context 'when a object pool was joined' do
+      let(:project) { create(:project, :repository, wiki_enabled: false, repository_read_only: true) }
+      let(:pool) { create(:pool_repository, :ready, source_project: project) }
+
+      it 'leaves the pool' do
+        allow_any_instance_of(Gitlab::Git::Repository).to receive(:fetch_repository_as_mirror).and_return(true)
+
+        subject.execute('test_second_storage')
+
+        expect(project.reload_pool_repository).to be_nil
+      end
+    end
   end
 end