Publish matrix mislabels the develop leg as a public release: NBGV drops the prerelease tag, NuGet package published as stable

[ptr727]

Summary

When publish-release.yml runs from the default branch (main) — via schedule or workflow_dispatch — the matrix builds both the main and develop legs. The develop leg's NBGV SemVer2 is computed without its prerelease (-g<sha>) suffix, so:

• the NuGet package is pushed as a stable / non-prerelease version (isPrerelease=false), and
• the GitHub release tag is a clean X.Y.Z.

The GitHub release object is still correctly flagged prerelease: true (via build-release-task.yml → prerelease: ${{ inputs.branch != 'main' }}), which masks the problem: the release looks like a prerelease while the NuGet package and version string are not.

Impact

Every non-default-branch (develop) publish since the "dispatch-from-main, matrix builds both branches" model was adopted pushes a non-prerelease NuGet package. Consumers running dotnet add package <id> without --prerelease can resolve a develop build as if it were stable.

Observed in a derived repo: develop builds 1.3.8, 1.3.10, 1.4.1 were all published to NuGet with clean version strings and isPrerelease=false, despite being develop prereleases (and correctly flagged prerelease on the GitHub release).

Root cause

get-version-task.yml checks out inputs.ref (the leg's branch) and runs dotnet/nbgv@master. NBGV computes PublicRelease by matching version.json's publicReleaseRefSpec (^refs/heads/main$) against the branch reported by its GitHub Actions cloud-build provider, which reads GITHUB_REF.

On a publish triggered from main, GITHUB_REF=refs/heads/main for the entire run regardless of which ref each matrix leg checks out. So the develop leg is classified PublicRelease=true, and NBGV strips the -g<sha> prerelease suffix → clean X.Y.Z.

This is specific to the matrix publisher: a direct push-to-develop build runs with GITHUB_REF=refs/heads/develop and versions correctly. The regression appeared when publishing moved to the dispatch-from-main matrix.

Proposed fix

1. Make NBGV version against the leg's branch. In get-version-task.yml, add a branch input (the publisher already threads a logical branch through build-release-task.yml) and pin the ref NBGV reads for that step:

   - name: Run Nerdbank.GitVersioning tool step
     id: nbgv
     uses: dotnet/nbgv@master
     env:
       # NBGV derives PublicRelease from the CI branch (GITHUB_REF). On a publish dispatched from the default
       # branch, every leg would otherwise be versioned as the public ref and lose its prerelease tag. Pin the
       # branch NBGV sees to the leg actually being versioned.
       GITHUB_REF: refs/heads/${{ inputs.branch }}
       GITHUB_REF_NAME: ${{ inputs.branch }}

   and have build-release-task.yml pass branch: ${{ inputs.branch }} to get-version-task.yml.

2. Add the inverse backstop. build-release-task.yml already fails a branch == 'main' build whose SemVer2 carries a prerelease - ("Verify public release version" step). Add the symmetric guard: a branch != 'main' build whose SemVer2 has no prerelease suffix should fail loudly, so a future "develop published as stable" regression can't slip through silently.

Repro

Dispatch publish-release.yml from main; inspect the develop leg's get-version SemVer2 (clean X.Y.Z, missing -g<sha>) and the resulting NuGet package (isPrerelease=false).

[ptr727]

Fixed on develop via #215 (5adbcb9). The fix is merged to the integration branch; it ships to consumers on the next develop → main release (two-phase model). Closing now rather than waiting for the default-branch auto-close.