external_merge: pass the repo_path to the merge tool

[wetneb]

This follows Git's merge driver interface which makes this information available using the %P variable. It is useful for merge drivers to adapt their behaviour based on the type of file supplied.

The motivation for this is that Mergiraf uses this information to determine the format of the file and parse its revisions accordingly. When the file format is determined by the file extension only, there is no need for this extra information as the file names of the base, left and right revisions will still have this extension (such as base_main.rs, left_main.rs, right_main.rs). But for files where the format is recognized by matching the entire file name, this will not work: base_Makefile isn't recognized on its own. However, when -p src/Makefile is provided, the tool is able to pick the right parsers.

Checklist

If applicable:

• I have updated CHANGELOG.md
• I have updated the documentation (README.md, docs/, demos/)
• I have updated the config schema (cli/src/config-schema.json)
• I have added/updated tests to cover my changes. (This area of the code does not seem to have any tests as far as I can tell)

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[OvidiusCicero]

@jj-vcs/maintainers can someone please have a look?

I like it and the implementation seems quite reasonable to me

[bnjmnt4n]

SGTM. I suspect we might want to rename the variable to $path instead for consistency withjj fix.

[yuja]

Thanks.

[algmyr]

So what should have happened here is that you should have been added to contributors so you can merge your own PR. I'll merge it for now, but some maintainer should give you the role for future PRs.

[wetneb]

@algmyr fascinating! I'm very interested in FOSS governance so I'm curious how this invitation to the contributors team is supposed to happen. Is there some automation behind it, perhaps? Or is it the responsibility of a particular person/team?

[algmyr]

There is no automation at the moment, and I think only the team of Maintainers have the power to give the membership. Sadly forgetting to add people happens more often than it should.

I hope #7606 should help with the not forgetting part once we get that in.

@jj-vcs/maintainers Can anyone add wetneb to contributors?