add publishing of latest-green.txt to jenkins e2e tests on success

hack/jenkins/e2e.sh

@@ -338,7 +338,12 @@ fi
 # Jenkins will look at the junit*.xml files for test failures, so don't exit
 # with a nonzero error code if it was only tests that failed.
 if [[ "${E2E_TEST,,}" == "true" ]]; then
-    go run ./hack/e2e.go ${E2E_OPT} -v --test --test_args="${GINKGO_TEST_ARGS}" || true
+    go run ./hack/e2e.go ${E2E_OPT} -v --test --test_args="${GINKGO_TEST_ARGS}" && exitcode=0 || exitcode=$?
+    if [[ "${E2E_PUBLISH_GREEN_VERSION:-}" == "true" && ${exitcode} == 0 && -n ${githash:-} ]]; then
+        echo "publish githash to ci/latest-green.txt: ${githash}"
+        echo "${githash}" > ${WORKSPACE}/githash.txt
+        gsutil cp ${WORKSPACE}/githash.txt gs://kubernetes-release/ci/latest-green.txt
+    fi
 fi
 
 # TODO(zml): We have a bunch of legacy Jenkins configs that are