Re: Discuss GSOC: Refactoring in order to reduce Git’s global state

> Yeah, things depending on `startup_info` are definitely a more involved
> thing to address, and I wouldn't necessarily recommend it for the
> initial batch of refactorings. I'd recommend to rather focus on some of
> the global variables we have in "environment.c" that store configuration
> values, which are generally a bit easier to tackle.
>
> Also note that `local_repo_env[]` is nothing that we need to adapt. It
> only stores a couple of environment variable names and does not have any
> state, so it's perfectly fine to keep that variable.

> It would be a bit more involved than a typical microproject, but I don't
> think it's particularly bad. It would involve a couple of steps:
>
>   - Investigate all users of the `git_attributes_file` global variable
>     and how they interact with the variable.
>
>   - Adapt `git_attr_global_file()` so that it knows to not only handle
>     the fallback value of `xdg_config_home("attributes")`, but also
>     knows to first read the value from the config.
>
>   - Adapt `git_attr_global_file()` so that it accepts a repository as
>     parameter so that it doesn't need to depend on `the_repository`.
>     This will also require you to adapt all callers.
>
> You _can_ use this as a microproject, but as said it's a bit more
> involved than what we'd expect. Which isn't necessarily bad if you
> manage to pull it off, but might make for a bit of a steep learning
> curve.