code: func (n *NsenterMounter) IsLikelyNotMountPoint(file string) (bool, error) {
  	file, err := filepath.Abs(file)
  	if err != nil {
  		return true, err
  	}
  
  	args := []string{"--mount=/rootfs/proc/1/ns/mnt", "--", n.absHostPath("findmnt"), "-o", "target", "--noheadings", "--target", file}
  	glog.V(5).Infof("findmnt command: %v %v", nsenterPath, args)
  
  	exec := exec.New()
  	out, err := exec.Command(nsenterPath, args...).CombinedOutput()
  	if err != nil {
  		glog.Errorf("Failed to nsenter mount, return file doesn't exist: %v", err)
  		// If the command itself is correct, then if we encountered error
  		// then most likely this means that the directory does not exist.
  		return true, os.ErrNotExist
  	}
  	strOut := strings.TrimSuffix(string(out), "\n")
  
  	glog.V(5).Infof("IsLikelyNotMountPoint findmnt output: %v", strOut)
  	if strOut == file {
  		return false, nil
  	}
  
  	return true, nil
  }
docs: // IsLikelyNotMountPoint determines whether a path is a mountpoint by calling findmnt
  // in the host's root mount namespace.