Fixed race with Post request and PollingRequestHandler triggering events nearly synchronously

- Not sure how this was reproduced "easily", it's a super small race (an
entire function has to execute before executing a single line).
- Lastly with this fix, it deems that this is not a regression but
rather just a very difficult stress bug to repro
- I was unable to reproduce the issue due to the craziness of the race.

#1776