Fix deploy workflow (take 2)

Generate data after merging; only merge when main has changed. Fixes #1125.

.github/workflows/build-and-deploy.yml

@@ -8,6 +8,10 @@ on:
       - main
   workflow_dispatch: # Allows manual trigger
 
+concurrency:
+  group: build-and-deploy
+  cancel-in-progress: false
+
 jobs:
   build_and_deploy:
     runs-on: ubuntu-latest
@@ -16,7 +20,7 @@ jobs:
       - name: Check out the repository
         uses: actions/checkout@v4
         with:
-          fetch-depth: 0 # Fetch full history to support rebasing
+          fetch-depth: 0 # Fetch full history for proper merging
 
       - name: Set up SSH for Git (deploy key)
         run: |
@@ -35,41 +39,33 @@ jobs:
           python3 -m pip install --upgrade pip
           pip install -r requirements.txt
 
-      - name: Generate Merged Data
-        run: |
-          python3 gh-data.py
-          python3 merge-data.py
-
-      - name: Switch to `gh-pages` and Preserve Changes
+      - name: Configure Git User
         run: |
           git config --global user.name "github-actions[bot]"
           git config --global user.email "github-actions[bot]@users.noreply.github.com"
 
-          # Stash changes to preserve them
-          git stash --include-untracked
-
-          # Fetch and switch to `gh-pages`
-          git fetch origin gh-pages:gh-pages || git checkout --orphan gh-pages
+      - name: Fetch and Check Out `gh-pages`
+        run: |
+          git fetch origin gh-pages:gh-pages
           git checkout gh-pages
 
-          # Rebase `gh-pages` onto `main` to ensure a linear history
-          git rebase main
+      - name: Merge `main` into `gh-pages` with `-s theirs`
+        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+        run: |
+          git merge ${{ github.sha }} -s theirs --no-edit
 
-          # Apply stashed changes
-          git stash pop || echo "No changes to apply."
+      - name: Generate Merged Data
+        run: |
+          python3 gh-data.py
+          python3 merge-data.py
 
       - name: Commit and Push Updates
         run: |
           # Add changes
           git add -f merged-data.json
-          git add .
 
           # Commit changes if there are any
-          if git diff --cached --quiet; then
-            echo "No changes to commit."
-          else
-            git commit -m "Update GitHub Pages with latest data"
-          fi
+          git commit -m "Update GitHub Pages with latest data"
 
           # Push changes back to `gh-pages`
           git remote set-url origin [email protected]:${{ github.repository }}.git