Improve commit messages for nightly releases

.github/workflows/ci.yml

@@ -35,6 +35,7 @@ jobs:
       run: |
         echo REPOSITORY_NAME=$(echo "$GITHUB_REPOSITORY" | awk -F / '{print $2}' | sed -e "s/:refs//") >> $GITHUB_ENV
         echo DATETIME=$(echo $(date '+%Y%m%d-%H%M%S')) >> $GITHUB_ENV
+        echo COMMIT_MESSAGES=$(echo "${{join(github.event.commits.*.message, '||END||') }}" |  sed -e 's/||END||/\r\n/g') >> $GITHUB_ENV
     - uses: actions/download-artifact@master
       with:
         name: binary
@@ -53,7 +54,7 @@ jobs:
         prerelease: true
         body: |
            Not a stable release:
-           ${{ github.event.head_commit.message }}
+           ${{ env.COMMIT_MESSAGES }}
     - name: Upload Release Asset
       id: upload-release-asset 
       uses: actions/upload-release-asset@v1