Comment 4 for bug 1953050

There is upgrade impact associated with the change, if "newer" services have to pick up and process messages from "older" services - with this change, they will be on a different exchange, so they won't see any messages.

To avoid this, olso.m should provide a fallback mechanism to cover cases when that "old" default exchange disappears. For example, some dispatcher there could introduce by default twice shared control exchanges, one durable by default and the other not, and a switch to decide to publish on one or the other (a dispatcher).