Start adding tests for verifying correct modes

Add an example for permission bits checking

pkg/volume/git_repo/git_repo.go

@@ -236,7 +236,7 @@ func (b *gitRepoVolumeMounter) SetUpAt(dir string, mounterArgs volume.MounterArg
 		return fmt.Errorf("failed to exec 'git reset --hard': %s: %v", output, err)
 	}
 
-	volume.SetVolumeOwnership(b, mounterArgs.FsGroup, nil)
+	volume.SetVolumeOwnership(b, mounterArgs.FsGroup, nil /*fsGroupChangePolicy*/)
 
 	volumeutil.SetReady(b.getMetaDir())
 	return nil