It's hard to trigger the failure to exit the rate limit state in
isolation as it needs multiple event sources in order to show that it
gets stuck in the queue. Hence why this is an extended test.

Instead of ordering non-pending before pending we should order
"non-pending OR ratelimited" before "pending AND not-ratelimited".
This fixes a bug where ratelimited events were ordered at the end of the
priority queue and could be stuck there for an indeterminate amount of
time.