Hi Limin,
I reproduced the issue and as you mentioned, I see different behaviors when I run it in Cloud Shell and when I deploy the app in App Engine. It seems like a bug. So, I created a report in the Issue Tracker <https://issuetracker.google.com/112718663> so that the issue be investigated by the Cloud App Engine team. You may star the report <https://issuetracker.google.com/112718663>for all further updates. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/google-appengine. To view this discussion on the web visit https://groups.google.com/d/msgid/google-appengine/d9fae056-706f-4601-8d59-cae8a98134e4%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
