build: guard against missing commit hash

Planeshifter · Planeshifter · commit 83cf2058d771 · 2023-12-07T22:32:38.000-05:00
diff --git a/.github/workflows/run_affected_tests.yml b/.github/workflows/run_affected_tests.yml
@@ -136,12 +136,18 @@ jobs:
             ancestor_commit=$(git merge-base ${{ github.event.pull_request.base.sha }} ${{ github.event.pull_request.head.sha }})
             files=$(git diff --diff-filter=AM --name-only $ancestor_commit ${{ github.event.pull_request.head.sha }})
           else
-            # Get changed files by comparing the current commit to the commit before the push event or with its parent:
+            # Check if the commit SHA exists:
+            if git rev-parse ${{ github.event.before }} >/dev/null 2>&1 && git rev-parse ${{ github.event.after }} >/dev/null 2>&1; then
+              # Get changed files by comparing the current commit to the commit before the push event or with its parent:
               if [ "${{ github.event.before }}" == "0000000000000000000000000000000000000000" ]; then
                 files=$(git diff --diff-filter=AM --name-only HEAD~ ${{ github.event.after }})
               else
                 files=$(git diff --diff-filter=AM --name-only ${{ github.event.before }} ${{ github.event.after }})
               fi
+            else
+              echo "Commit SHA not found, skipping file changes detection..."
+              files=""
+            fi
           fi
           directories=$(for file in $files; do dirname $file; done | uniq | tr '\n' ' ' | sed 's/ $//')
           echo "directories=${directories}" >> $GITHUB_OUTPUT
