The JobExecutor class in the EventBus extension duplicates a lot of complex code from core's JobRunner class. It should be reconsiled with JobRunner and deleted from EventBus. JobRunner should either expose the relevant interface for running a job directly from a spec array, the relevant functionality should be factored out. The latetr would effectively mean that JobExecutor is moved into core, and JobRUnner uses it.

Note that JobExecutor is not used in the EventBus extension at all. It is used only by RunSingleJob, which is a Wikimedia-specific private rpc endpoint maintained in the mediawiki-config repo. RunSingleJob is called by the changeprop service per wmf deployment config.