Merge pull request #306 from AArnott/libtemplateWorkflowUpdates

Self-updating workflow updates

.github/workflows/libtemplate-update.yml

@@ -13,12 +13,16 @@ on:
 jobs:
   merge:
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
     steps:
     - uses: actions/checkout@v4
       with:
         fetch-depth: 0 # avoid shallow clone so nbgv can do its work.
 
     - name: merge
+      id: merge
       shell: pwsh
       run: |
         $LibTemplateBranch = & ./azure-pipelines/Get-LibTemplateBasis.ps1 -ErrorIfNotRelated
@@ -31,15 +35,18 @@ jobs:
           exit $LASTEXITCODE
         }
         $LibTemplateCommit = git rev-parse FETCH_HEAD
+        git diff --stat ...FETCH_HEAD
 
         if ((git rev-list FETCH_HEAD ^HEAD --count) -eq 0) {
           Write-Host "There are no Library.Template updates to merge."
+          echo "::set-output name=uptodate::true"
           exit 0
         }
 
         git -c http.extraheader="AUTHORIZATION: bearer $env:GH_TOKEN" push origin -u FETCH_HEAD:refs/heads/auto/libtemplateUpdate
     - name: pull request
       shell: pwsh
+      if: success() && steps.merge.outputs.uptodate != 'true'
       run: |
         # If there is already an active pull request, don't create a new one.
         $existingPR = gh pr list -H auto/libtemplateUpdate --json url | ConvertFrom-Json