It appears the continuous stepdown hook can get in a situation where

1) It steps up a secondary.

2) The secondary becomes primary, but is slow to get all the way to writable primary (e.g. due to catch-up)

3) The hook steps up another secondary

4) Election fails

5) The hook goes to step up the original primary, which is fine (it's already primary).

6) The primary finishes catch-up, and steps down due to the term change.

7) We're now without a primary until election timeout expires. (very bad with high election timeout).

We should also add logging to the hook so all these steps are visible.