1. Checkout to master.
2. Log-out.
3. Log-in.
4. Checkout to the branch with this diff stack.
Then:
5. Using mariadb console ensure that new olm session was created on the keyserver.
6. Using Developer Tools ensure that new entry was created in `IndexedDB` and that it contains pickled olm session for notifs.
7. Log-out.
8. Using Developer Tools ensure that entry with olm session for notifs was removed (it is not implemented in this differential but this line(https://github.com/CommE2E/comm/blob/master/web/database/worker/db-worker.js#L154) should clear entire `IndexedDB` on log-out).