This fixes a bug where 'Worker undefined changed status' was logged in
the web interface, as that was (back then incorrectly) `workerupdate.name`.
Now that code is correct.
A worker state change request can now be cancelled by requesting the worker
to go to its current state. In other words, a previously requested change
`A → B` can be cancelled by requesting the worker goes to state `A`.
Previously this would simply overwrite the last request, resulting in a
requested state change `A → A`. Having this non-lazy would even interrupt
the currently running task.
