Add parent PR title to cherry-picked PR title

Author: xiangpengzhao

Diff for: hack/cherry_pick_pull.sh

@@ -131,12 +131,13 @@ function make-a-pr() {
   # when we shove the heredoc at hub directly, tickling the ioctl
   # crash.
   prtext="$(mktemp -t prtext.XXXX)" # cleaned in return_to_kansas
+  local numandtitle=$(printf '%s\n' "${SUBJECTS[@]}")
   cat >"${prtext}" <<EOF
-Automated cherry pick of ${PULLSUBJ}
+Automated cherry pick of ${numandtitle}
 
 Cherry pick of ${PULLSUBJ} on ${rel}.
 
-$(printf '%s\n' "${SUBJECTS[@]}")
+${numandtitle}
 EOF
 
   hub pull-request -F "${prtext}" -h "${GITHUB_USER}:${NEWBRANCH}" -b "kubernetes:${rel}"