ci: cherry-pick port-merge comment

.circleci/scripts/cherry-picker.sh

@@ -131,6 +131,16 @@ fi
 # save PR number
 pr_number=$(echo "$resp" | jq '.items[].number')
 
+# comment on the PR with the build number to make it easy to re-run the job when
+# cherry-pick labels are added in the future
+github_message=":cherries: Starting backport cherry picking.\n\nTo cherry-pick post-merge, add backport labels and re-run ${CIRCLE_BUILD_URL}."
+curl -f -s -H "Authorization: token ${GITHUB_TOKEN}" \
+    -X POST \
+    -d "{ \"body\": \"${github_message}\"}" \
+    "https://api.github.com/repos/${CIRCLE_PROJECT_USERNAME}/${CIRCLE_PROJECT_REPONAME}/issues/${pr_number}/comments"
+
+
+
 # If the API returned a non-zero count, we have found a PR with that commit so we find
 # the labels from the PR