robust handling of vat termination by Zoe across Zoe upgrades

[Chris-Hibbert]

See: #8263

What is the Problem Being Solved?

Zoe queues up handling of vat termination in local promises which would be smashed by upgrade of the Zoe vat.

Description of the Design

Handle (and test handling of) resetting those handlers when Zoe upgrades.

Security Considerations

Any guarantees about final processing or notification should survive upgrade.

Scaling Considerations

Not a huge deal. Has to be managed once per contract.

Test Plan

use upgrade tests.

Upgrade Considerations

Yep, that's what it's about.