Re: Bug: `git init` with hook `reference-transaction` running `git rev-parse --git-dir` fails

[Patrick Steinhardt <ps@pks.im>]

On Mon, Oct 07, 2024 at 01:02:56PM +0200, Gabriel Nützi wrote:
> Ah, jeah thats true:
> 
> The command in question which is `git rev-parse --git-dir` to find the actual GIT_DIR is actually the issue here:
> It relies on having a proper HEAD despite the docs saying it only reports GIT_DIR if set etc...

That's not quite true. The second paragraph for the `--git-dir` option
in git-rev-parse(1) has this to say:

    If $GIT_DIR is not defined and the current directory is not detected to lie in a Git
    repository or work tree print a message to stderr and exit with nonzero status.

But in our case you're correct: `$GIT_DIR` _is_ defined during hook
execution. So in theory, if git-rev-parse(1) behaved exactly as
documented, it shouldn't even care whether or not it is executing in a
repository.

> Could we maybe make these commands more agnostic? 

So this could indeed be a viable fix, but I guess we'd rather play
whack-a-mole because other Git commands that one may want to execute in
this repository would also be broken.

> Making an empty HEAD probably directly also resolves these commands to work correctly.

So agreed, creating a stub HEAD is the most sensible option we have. I'd
like to wait a bit for more feedback from other contributors before we
do so though.

Patrick