When a change is done on an issue of a short living branch and if configuration is appropriate, webhooks of the current project and/or defined at global level are called.
This is currently done synchronously from the HTTP request's thread.
This works, but the time taken by the HTTP call(s) to notify webhooks is added to the time the
HTTP request takes to be processed by SQ's WebServer.
If the remote server called though HTTP is slow, the HTTP request will be slowered by as much.
Therefor, webhook calls must be made asynchronously.
In addition, code added to support asynchronously called webhooks must be designed so that a privileged plugin (or another piece of SQ's code) can also have some other code be run asynchronously. The scope is currently limited to the PR decoration feature.