A puzzle: reset --hard and hard links

From: Michael Herrmann <michael@herrmann.io>
Date: Jan 19, 2022, 20:37 UTC
Message-ID: <CABrKpmDseZkPCpRb8KmBJaxDp24sySJay5ffZrxqgSMGKyj5qQ@mail.gmail.com>

Hi all,

It seems `git reset --hard` recreates files that have external hard links. Is this intended?

The example below highlights the behavior. I have an unchanged Git repository. When I create an (outside) hard link to a file in the repository, then `git reset --hard` re-creates the file with a new modification time and inode. This occurs on Debian 11 with Git 2.30.2 but not on Debian 10 with Git 2.20.1

> git init

Initialized empty Git repository in .../git-test/.git/

> echo "test" > file.txt
> git add file.txt
> git commit -m "Import"

[main (root-commit) f73709f] Import
 1 file changed, 1 insertion(+)
 create mode 100644 file.txt

> stat -c '%y' file.txt

2022-01-19 18:43:52.147781748 +0100

> ls -i file.txt

74458979 file.txt

> ln file.txt ../file.txt
> git reset --hard

HEAD is now at f73709f Import

> stat -c '%y' file.txt

2022-01-19 18:44:47.013167127 +0100

> ls -i file.txt

74458995 file.txt

Can this behavior be avoided?

Best, Michael