Leaving a room sometimes doesn't remove it from the room list

This has happened several times to me in the past few months:

Steps to reproduce:
1. Leave a room
2. Observe that instead of being dumped back in the room list, you're still in the room timeline even though it's clear that you left:
3. Leaving the room again makes it disappear from the room list

Start by reproducing the three steps in the Element X Android app and trace the room-leave handling between the room timeline and room list. Done means leaving once removes the room from the list and returns the user to the room list instead of leaving the timeline visible.

Written by the indexing model from the issue text.