Fix implicit task unpause when going from 'running' to 'idle'.
If a task is running and we call isc_task_pause it can be implicitly unpaused when we switch from 'running' to 'idle' state. Fix it by not switching to 'idle' when paused.
If a task is running and we call isc_task_pause it can be implicitly unpaused when we switch from 'running' to 'idle' state. Fix it by not switching to 'idle' when paused.