Feat: Add path_prefix output for downstream actions

[ModeSevenIndustrialSolutions]

When using path_prefix to build projects in subdirectories, downstream actions like python-test-action, python-audit-action, and python-sbom-action also need the same path_prefix value. This change outputs path_prefix so others can consume it with needs.python-build.outputs.path_prefix.

Also, mandatory tests were failing on this PR which required additional updates.

• Make Git unshallow step conditional (this was causing some tox builds to fail)

Spurious code was previously committed containing shell set commands in various steps. These were mistakenly placed above comments, and often enabled pipefail in steps that did not contain any pipes, also adding options that overlapped with the GitHub default behaviours. Removing these lines cleans up mostly useless/boilerplate code.

[Copilot]

Pull request overview

This PR adds a path_prefix output to the python-build-action to facilitate passing the path prefix value to downstream actions when building Python projects in subdirectories. This addresses issue #138 by allowing workflows to reference needs.python-build.outputs.path_prefix instead of having to manually duplicate the value.

Changes:

• Added path_prefix output to action.yaml that exposes the input value
• Updated outputs documentation table in README.md
• Added comprehensive usage example showing how to pass path_prefix between jobs

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
action.yaml	Adds new path_prefix output that exposes the input value for downstream consumption
README.md	Documents the new output in the outputs table and provides a complete multi-job workflow example demonstrating its usage

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[ModeSevenIndustrialSolutions]

Tested here: https://github.com/modeseven-lfit/dependamerge/actions/runs/21702169170

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

action.yaml:284

• Removal of set -euo pipefail means pip install commands could fail silently without stopping the script. This could lead to builds proceeding with missing dependencies, which would cause failures later in the process. If the removal is intentional, explicit error handling should be added for all critical commands.

        # Install build dependencies
        echo 'Installing Python build dependencies...'
        python -m pip install --disable-pip-version-check \
          -q --upgrade build packaging
        echo 'Build dependencies installed ✅'

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