Run all vcs versioning processes locally

[benjyw]

When using environments we must ensure we run VCS-related
processes in the local environment and not the inherited one,
as a docker environment will not have access to Git state.

In #21188 we made setuptools_scm itself run locally,
but this was not sufficient: this change makes sure we
also run the pex building and git binary discovery
in the local environment.

Fixes #21178

[benjyw]

I'm looking into writing a test for this.

[huonw]

Thanks for this and explaining the git logic.

Just confirming why we need to build the pex locally too: the pex built in the docker environment might not be compatible with the local environment, e.g. if the host is macOS, and the docker environment is linux. Is that right?

[huonw]

Also, does this need cherrypicking to 2.22.x?

[benjyw]

Just confirming why we need to build the pex locally too: the pex built in the docker environment might not be compatible with the local environment, e.g. if the host is macOS, and the docker environment is linux. Is that right?

Correct - we have to build it where we run it.

[benjyw]

Also, does this need cherrypicking to 2.22.x?

The previous change wasn't. I was treating this as more of a feature than a bug, but that is admittedly debatable. I could CP both of them - yeah, might as well.

[benjyw]

OK, this is the CP for the previous part: #21355

Will then auto-CP this one on top of it.

[WorkerPants]

I tried to automatically cherry-pick this change back to each relevant milestone, so that it is available in those older releases of Pants.

❌ 2.22.x

I was unable to cherry-pick this PR to 2.22.x, likely due to merge-conflicts.

Steps to Cherry-Pick locally

To resolve:

1. (Ensure your git working directory is clean)
2. Run the following script to reproduce the merge-conflicts:

   git fetch https://github.com/pantsbuild/pants main \
     && git fetch https://github.com/pantsbuild/pants 2.22.x \
     && git checkout -b cherry-pick-21353-to-2.22.x FETCH_HEAD \
     && git cherry-pick 6a1a938787b7ef0f9ee2d5b14c436a1f84d5589a

3. Fix the merge conflicts and commit the changes
4. Run build-support/cherry_pick/make_pr.sh "21353" "2.22.x"

Please note that I cannot re-run CI if a job fails. Please work with your PR approver(s) to re-run CI if necessary.

---

When you're done manually cherry-picking, please remove the needs-cherrypick label on this PR.

Thanks again for your contributions!

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