* raise BackupAgentUnreachableError when NAS is unavailable
* also raise BackupAgentUnreachableError during upload when nas unavailable
* Revert "also raise BackupAgentUnreachableError during upload when nas unavailable"
This reverts commit 38877d8540.
* Revert "raise BackupAgentUnreachableError when NAS is unavailable"
This reverts commit 4d8cfae396.
* check last_update_success of coordinator_central to get backup agents
* consider last_update_success before notify backup listeners
* add test
* use walrus := :)