debugf("renaming %q", slashpath.Join(dir, tmpBase))
err = unix.Renameat(parentFd, tmpBase, parentFd, baseName)
if err != nil {
debugf("renaming %q", slashpath.Join(dir, tmpBase))
err = unix.Renameat(parentFd, tmpBase, parentFd, baseName)
if err != nil {