Missed deletions in multi server environment
Assuming we work in an multiserver ISPConfig setup, let's start with an example:
if one website with an associated FTP user exist in one of the available servers, lets say that it is called web1, if subsequently the FTP user's "Site" attribute is modified with another available website in another webserver, called web2, a new FTP user in web2 is created, but the original FTP user is not deleted in web1.
This happens also in other contexts, such as changing domain in mailboxes, website alias domain and subdomain, shell users and cron jobs. Please note that this list may not be complete.
We think that the cause of this problem may be the "update" trigger implementation in each of the plugin classes, that seem to ignore that the origin and destination servers are different, and consequently don't insert a deletion work.