When the PR bot updates the body of a PR, it can race with the author making an update around the same time. This can cause the new description provided by the author to get immediately overwritten with the old description by the bot.

I don't think there is any way of avoiding this race, but we could at least try to minimize the potential window. Currently the PR data, including the body, is fetched when the CheckWorkItem begins executing. The current body is never refreshed from the server after that. We should at the very least fetch PR data again right before trying to update the body and verify that nothing changed.