Fix review request caching when issue statuses change.
Review Request #3568 — Created Nov. 27, 2012 and submitted
Fix review request caching when issue statuses change. Our review request page's etags didn't take into account any state changes caused by when issues were opened/closed. That's because we didn't have anything we updated under those cases. We're now repurposing the ReviewRequest.last_review_timestamp, which was no longer used. This has been renamed last_review_activity_timestamp in order to be a little more clear, and has a comment describing what it takes into account. Unit tests were added to make sure this doesn't regress.
Started with the unit test, which failed originally, showing that the etags matched before and after changing the issue status. After the change, the unit test passed. I also reproduced it through the browser. Originally, if you opened two tabs to the same page, closed the issue in one, and then entered the URL again on the second, the issue would appear opened. After this change, that doesn't happen, and the new load shows the correct state.