Control scripts determine the sections to use, so there is no current section yet while control scripts are running.
The merge engine performs the following steps:
Run control scripts, during which sections can be enabled/disabled or cloned
For each enabled section/clone: Run standard scripts
2a. Paginate, during which master pages are applied
2b. For each applied master page: Run standard scripts
For each enabled section/clone: Run post-pagination scripts
For standard scripts and post-pagination scripts “merge.section” returns the current section.