Zero-Downtime broken when updating startsecs

[jone]

When an upgrade is deployed, where zero-downtime is active and the supervisor startsecs are changed in the update, the instances are restarted in parallel, but should be restarted serially (since zero-downtime active).

Suspicion:

The script does a bin/supervisorctl update instance1, while instance1 is stopped. When there is no change, nothing happens. But when there is a change in the supervisor config, the new config is loaded an the autostart-setting will cause the instance to be started.
The problem is that supervisor now starts the instance but this is not blocking and the next start instance1 command will be instantly terminated since the instance is already starting. Normally start instance1 would block for startsecs time, so that the instances are properly restarted serially.

This probably needs to be fixed in supervisor.