[DGD] Callout delays are now advisory?

[Shentino]

Just had a little chat with felix on dgdhub, and found out that callouts
with distinct delays of the same type, started from the same ER, are no
longer guaranteed to execute in any order.

Once a callout expires, it enters the pending cloud and can mingle with any
other such callouts until it gets picked to fire.

Apparently the change was made to enhance Hydra's parallelism.

Just confirming this tidbit and making it public, since it apparently missed
the Changelog.