I started to wonder quite recently why Hydra doesn't send email
notifications anymore to me. I saw the following issue in the log of
`hydra-notify.service`:
May 22 11:57:29 hydra 9bik0bxyxbrklhx6lqwifd6af8kj84va-hydra-notify[1887289]: fatal: unsafe repository ('/var/lib/hydra/scm/git/3e70c16c266ef70dc4198705a688acccf71e932878f178277c9ac47d133cc663' is owned by someone else)
May 22 11:57:29 hydra 9bik0bxyxbrklhx6lqwifd6af8kj84va-hydra-notify[1887289]: To add an exception for this directory, call:
May 22 11:57:29 hydra 9bik0bxyxbrklhx6lqwifd6af8kj84va-hydra-notify[1887289]: git config --global --add safe.directory /var/lib/hydra/scm/git/3e70c16c266ef70dc4198705a688acccf71e932878f178277c9ac47d133cc663
May 22 11:57:29 hydra 9bik0bxyxbrklhx6lqwifd6af8kj84va-hydra-notify[1886654]: error running build_finished hooks: command `git log --pretty=format:%H%x09%an%x09%ae%x09%at b0c30a7557685d25a8ab3f34fdb775e66db0bc4c..eaf28389fcebc2beca13a802f79b2cca6e9ca309 --git-dir=.git' failed with e>
This is also a problem because of Git's fix for CVE-2022-24765[1], so I
applied the same fix as for Nix[2], by using `--git-dir` which skips the
code-path for the ownership-check[3].
[1] https://lore.kernel.org/git/xmqqv8veb5i6.fsf@gitster.g/
[2] https://github.com/NixOS/nix/pull/6440
[3] To quote `git(1)`:
> Specifying the location of the ".git" directory using this option
> (or GIT_DIR environment variable) turns off the repository
> discovery that tries to find a directory with ".git" subdirectory
a8b590014b