problem

The editor_Models_Import_Worker_SetTaskToOpen and editor_Models_Import_Worker_FinalStep workers are initialized with no explicit status so the default scheduled is used. But: all other import workers are added with status prepare so that plugins are able to add other workers also.

That lead to the seldom situation where the SetTaskToOpen and FinalStep workers are triggered before the other workers are even ready to run. How that can be is still unclear since the scheduler also checks for prepared dependency workers. However, the usage of the prepare state instead schedule should resolve the problem here.

This can lead to tasks with no segments, producing errors like

ZfExtended_Models_Entity_NotFoundException: Foldertree Entity Not Found

on task usage.