EXDEV when re-init with --separate-git-dir option

Dear maintainers,

We discovered that re-init with option --separate-git-dir will throw an EXDEV when the target directory is not on the same file system as the original directory.

An example is shown below:

$ mkdir -p fs1/gitdir fs2 $ ls fs1 fs2 $ sudo mount -t tmpfs tmpfs fs2 $ cd fs1/gitdir $ git init Initialized empty Git repository in /home/user/fs1/gitdir/.git/ $ git init --separate-git-dir ../../fs2/surrealgitdir fatal: unable to move /home/user/fs1/gitdir/.git to /home/user/fs2/surrealgitdir: Invalid cross-device link

We tested this on version v2.45.2 and after reading the code a bit we believe the issue still exist in the master branch on github (https://github.com/git/git/blob/d19b6cd2dd72dc811f19df4b32c7ed223256c3ee/setup.c#L2280).

Best regards, Di