fix(repo): don't try to fetch master if already on master (#29831)

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Fixes #

.github/workflows/ci.yml

@@ -34,6 +34,8 @@ jobs:
 
       - name: Fetch Master
         run: git fetch origin master:master
+        if: ${{ github.event_name == 'pull_request' }}
+        
 
       - name: Set SHAs
         uses: nrwl/nx-set-shas@v4