Fix detached-SHA versioning: branch input + git checkout -B (completes IGNORE_GITHUB_REF)

.github/workflows/build-nugetlibrary-task.yml

@@ -37,6 +37,7 @@ jobs:
     secrets: inherit
     with:
       ref: ${{ inputs.ref }}
+      branch: ${{ inputs.branch }}
 
   build-nugetlibrary:
     name: Build NuGet library project job

.github/workflows/build-release-task.yml

@@ -50,6 +50,7 @@ jobs:
     secrets: inherit
     with:
       ref: ${{ inputs.ref }}
+      branch: ${{ inputs.branch }}
 
   # Entry gate: validate branch<->version consistency once, before the build jobs, so an NBGV mis-classification fails
   # fast instead of after building and publishing. main must be a public release (no prerelease '-'); every other branch

.github/workflows/get-version-task.yml

@@ -9,6 +9,13 @@ on:
         required: false
         type: string
         default: ''
+      # Logical branch NBGV classifies public-vs-prerelease against. With IGNORE_GITHUB_REF, NBGV reads the
+      # checked-out git branch; callers that check out a pinned commit (detached HEAD - the build jobs) pass this
+      # so a local branch can be created at that commit, giving NBGV the right name. Empty leaves the checkout as-is.
+      branch:
+        required: false
+        type: string
+        default: ''
     outputs:
       SemVer2:
         value: ${{ jobs.get-version.outputs.SemVer2 }}
@@ -47,6 +54,16 @@ jobs:
           ref: ${{ inputs.ref }}
           fetch-depth: 0
 
+      # NBGV (with IGNORE_GITHUB_REF) classifies public-vs-prerelease from the checked-out branch. A pinned-SHA
+      # checkout is detached HEAD, where NBGV sees no branch and treats every leg as prerelease (the main leg would
+      # then build a prerelease package mismatching its clean release tag). Force a local branch at HEAD matching the
+      # logical branch so NBGV sees the right name while still versioning the intended commit.
+      - name: Pin logical branch step
+        if: ${{ inputs.branch != '' }}
+        env:
+          BRANCH: ${{ inputs.branch }}
+        run: git checkout -B "$BRANCH"
+
       # nbgv is floated on @master: its tag stream lags master, so Dependabot tag-tracking would propose a downgrade.
       # Revisit if dotnet/nbgv resumes regular tagged releases.
       - name: Run Nerdbank.GitVersioning tool step