fix: resolve heavy CI triggering on maintenance branches and git history issues

1. Remove *.*.x from continuous-integration.yml triggers
   - Heavy CI/CD builds now only run on main branch
   - Maintenance branches use only the fast workflow

2. Fix git history availability in maintenance-fast.yml
   - Use fetch-depth: 2 to ensure HEAD~1 is available
   - Add debug logging for git state
   - Add fallback to "git show" when HEAD~1 not available

3. Improve error handling in test_discovery.py
   - Test for HEAD~1 existence before using it
   - Fallback to "git show --name-only HEAD" for shallow clones

This should resolve both the duplicate heavy workflows and the git diff failures.

Author: markpollack

.github/scripts/test_discovery.py

@@ -63,7 +63,17 @@ def _get_changed_files(self, base_ref: Optional[str] = None) -> List[str]:
             # For maintenance branches (cherry-picks), always use single commit diff
             if branch and branch.endswith('.x'):
                 # Maintenance branch - cherry-picks are always single commits
-                cmd = ["git", "diff", "--name-only", "HEAD~1..HEAD"]
+                # Try HEAD~1..HEAD first, fallback to different strategies if not available
+                try:
+                    # Test if HEAD~1 exists
+                    subprocess.run(["git", "rev-parse", "HEAD~1"], 
+                                 cwd=self.repo_root, check=True, capture_output=True)
+                    cmd = ["git", "diff", "--name-only", "HEAD~1..HEAD"]
+                except subprocess.CalledProcessError:
+                    # HEAD~1 not available (shallow clone), try other approaches
+                    print("HEAD~1 not available, trying alternative approaches", file=sys.stderr)
+                    # Try showing just the files in the current commit
+                    cmd = ["git", "show", "--name-only", "--format=", "HEAD"]
             elif base_ref:
                 # Explicit base reference provided - use two-dot diff for direct comparison
                 cmd = ["git", "diff", "--name-only", f"{base_ref}..HEAD"]

.github/workflows/continuous-integration.yml

@@ -4,7 +4,6 @@ on:
   push:
     branches:
       - main
-      - '*.*.x'
   workflow_dispatch:
 
 jobs:

.github/workflows/maintenance-fast.yml

@@ -15,9 +15,7 @@ jobs:
       cancel-in-progress: true
     steps:
       - uses: actions/checkout@v4
-        with: { fetch-depth: 0 }
-
-      - run: git fetch origin "$GITHUB_REF_NAME" --depth=1
+        with: { fetch-depth: 2 }  # Ensure we have at least HEAD~1 available
 
       - uses: actions/setup-java@v4
         with:
@@ -33,7 +31,10 @@ jobs:
       - name: Show commit range
         run: |
           echo "Base ref: origin/$GITHUB_REF_NAME"
-          git log --oneline "origin/$GITHUB_REF_NAME...HEAD"
+          echo "HEAD commit: $(git rev-parse HEAD)"
+          echo "HEAD~1 commit: $(git rev-parse HEAD~1 2>/dev/null || echo 'HEAD~1 not available')"
+          echo "Recent commits:"
+          git log --oneline -3 || echo "Git log failed"
 
       - name: Compute impacted modules
         id: mods