NO-JIRA: Handle upstream file deletions gracefully in restore-upstream step

When a file listed in restore-upstream is deleted in upstream, git
checkout --theirs fails as there is no upstream version to restore.
The step now checks each file's conflict status individually and runs
git rm for files deleted upstream (UD) instead of erroring out.

Signed-off-by: Jayapriya Pai <janantha@redhat.com>

Author: slashpai

.github/workflows/merge-flow.yaml

@@ -142,8 +142,19 @@ jobs:
         if: ${{ steps.merge.outputs.MERGE_CONFLICT == 'true' && inputs.restore-upstream != ''}}
         run: |
             echo "reset ${{ inputs.restore-upstream }}"
-            git checkout --theirs ${{ inputs.restore-upstream }}
-            git add ${{ inputs.restore-upstream }}
+            for file in ${{ inputs.restore-upstream }}; do
+              # Get the two-character porcelain status for this file (e.g. UU, UD, DU)
+              status=$(git status --porcelain "$file" 2>/dev/null | cut -c1-2 | tr -d ' ')
+              if [ "$status" == "UD" ]; then
+                # File was deleted in upstream - remove it from downstream as well
+                git rm "$file"
+              elif [ -n "$status" ]; then
+                # File exists in upstream - restore to upstream (theirs) version
+                git checkout --theirs "$file"
+                git add "$file"
+              fi
+              # If status is empty the file has no conflict, skip it
+            done
       - name: Resolve conflict using downstream contents
         if: ${{ steps.merge.outputs.MERGE_CONFLICT == 'true' && inputs.restore-downstream != ''}}
         run: |