This is the normal behaviour of bind mounts, introduced in Linux 2.4.0. If this is to be considered a bug in Linux, it's a very old one!
- [bug-diffutils] bug#33467: "diff" can not scan di... Delian Krustev
- [bug-diffutils] bug#33467: bug#33467: "diff"... Mark Raymond
- [bug-diffutils] bug#33467: bug#33467: bug#33467: &... Eric Blake
- [bug-diffutils] bug#33467: bug#33467: bug#3346... Eric Deplagne
- [bug-diffutils] bug#33467: bug#33467: &quo... Mark Raymond
- [bug-diffutils] bug#33467: bug#33467:... Eric Deplagne
- [bug-diffutils] bug#33467: bug#33... Mark Raymond
- [bug-diffutils] bug#33467: bug#33467: bug#3346... Delian Krustev
- [bug-diffutils] bug#33467: bug#33467: bug#... Eric Blake
- [bug-diffutils] bug#33467: bug#33467: bug#... Paul Eggert