Fetch history for the ref

action.yaml

@@ -8,15 +8,15 @@ runs:
       run: git fetch --unshallow
       shell: bash
 
-    - name: Ensure commits from forks are fetched (testing)
-      run: git ls-remote
+    - name: Support forks by grabbing the commit history from the PR branch
+      run: git fetch origin ${{ github.ref }}:updated_head_ref
       shell: bash
 
     - name: Check that every commit name includes an issue reference like "#1"
       run: |
         set -eo pipefail
         IFS=$'\n'
-        commits=$(git log --oneline origin/${{github.base_ref}}..origin/${{github.head_ref}})
+        commits=$(git log --oneline origin/${{github.base_ref}}..updated_head_ref)
         for commit in $commits
         do
           if [[ $commit =~ ^.*#[0-9]+.*$ ]];