Use NBGV IGNORE_GITHUB_REF instead of the ineffective GITHUB_REF override

[ptr727]

Problem

Closes #221; supersedes the mechanism from #215. The #213 fix (PR #215) restored the develop leg's prerelease tag by overriding GITHUB_REF in the nbgv step env:. It doesn't work. GITHUB_REF is GitHub-reserved — a step-level env: can't reliably override it (the runner re-injects the dispatch ref). NBGV's GitHub Actions cloud-build provider reads GITHUB_REF for BuildingRef, so on a publish dispatched from main the develop leg was still classified public and would publish a clean (stable) version.

CI evidence from the first real publish after #215:

GITHUB_REF: refs/heads/develop      # the step-env override (as configured)
"BuildingRef": "refs/heads/main"    # NBGV still saw the dispatch ref
"PublicRelease": true
"SemVer2": "1.4.2"                   # clean, no -g suffix

(The validate-release gate correctly blocked the bad publish, so nothing shipped — but the develop prerelease leg never publishes.)

Fix

NBGV versions from the checked-out branch unless its cloud provider overrides with GITHUB_REF. Each matrix leg already checks out its own branch, so set NBGV's own IGNORE_GITHUB_REF=true to make it ignore the CI ref:

      - name: Run Nerdbank.GitVersioning tool step
        id: nbgv
        uses: dotnet/nbgv@master
        env:
          IGNORE_GITHUB_REF: true

• Removed the ineffective GITHUB_REF/GITHUB_REF_NAME override.
• Dropped the now-useless branch input from get-version-task.yml and its threading from all five callers (build-release-task + the four build-*-task).
• validate-release entry gate (from Publish matrix mislabels the develop leg as a public release: NBGV drops the prerelease tag, NuGet package published as stable #213/Version each publish leg against its own branch; validate at entry #215, smoke-skip from validate-release gate fails main-base PR smoke builds, blocking develop->main promotions #219) stays as the backstop.

NBGV source confirms the knob: BuildingRef => IgnoreGitHubRef ? null : env GITHUB_REF.

Verification

• actionlint (Docker) clean on all six changed workflows; CRLF preserved.
• Per the issue's CI probe (real dotnet/nbgv): develop checkout + IGNORE_GITHUB_REF=true → PublicRelease=False, 1.4.2-g…; main → True, 1.4.3; main without the flag reproduces the bug.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes NBGV branch classification in the publish matrix by using NBGV's supported IGNORE_GITHUB_REF switch (so versioning follows the checked-out ref per leg) and removes the prior, ineffective GITHUB_REF override mechanism.

Changes:

• Set IGNORE_GITHUB_REF=true for the dotnet/nbgv@master step so NBGV ignores the workflow dispatch ref.
• Remove the now-unused branch input from get-version-task.yml.
• Remove branch: threading into get-version-task.yml from all reusable workflow callers.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.github/workflows/get-version-task.yml	Drop branch input and switch NBGV to IGNORE_GITHUB_REF for correct per-checkout versioning.
.github/workflows/build-release-task.yml	Stop passing branch into get-version-task.yml (versioning no longer relies on env overrides).
.github/workflows/build-pypilibrary-task.yml	Remove branch passthrough to get-version-task.yml.
.github/workflows/build-nugetlibrary-task.yml	Remove branch passthrough to get-version-task.yml.
.github/workflows/build-executable-task.yml	Remove branch passthrough to get-version-task.yml.
.github/workflows/build-docker-task.yml	Remove branch passthrough to get-version-task.yml.