3.16 and 3.15 branch status not refreshing

[hugovk]

Despite #714, 3.16 is still shown as "No branch" and 3.15 as "Feature branch main" at https://buildbot.python.org/#/release_status:

Looks like the problem is here:

        def main():
            force_refresh = request.args.get("refresh", "").lower() in {"1", "yes", "true"}

            if self.cache is not None and not force_refresh:
                result, deadline = self.cache
                if time.monotonic() <= deadline:
                    return result

                try:
                    self._refresh_branch_info()
                except urllib.error.HTTPError:
                    pass

            result = self.get_release_status()
            deadline = time.monotonic() + CACHE_DURATION

If it's a force refresh, we never hit self._refresh_branch_info().

If it's a cron run with no cache, we also never hit it.

Otherwise it's a cron run with a cache. The cron is every 5 mins, but the CACHE_DURATION is 6 minutes, so we'll never exceed that, and not hit it.